Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| alder fly, lacewing or snake fly | Chrysopa | a Chrysopa species (unidentified) | 8 | 2024 |
| alder fly, lacewing or snake fly | Chrysopa pallens | a green lacewing | 2 | 2009 |
| alder fly, lacewing or snake fly | Chrysopa perla | a green lacewing | 20 | 2023 |
| alder fly, lacewing or snake fly | Chrysoperla carnea group | a green lacewing | 66 | 2024 |
| alder fly, lacewing or snake fly | Chrysoperla lucasina | an insect - lacewing (Neuroptera) | 3 | 2013 |
| alder fly, lacewing or snake fly | Chrysopidae | a green lacewing (unidentified) | 14 | 2022 |
| alder fly, lacewing or snake fly | Chrysotropia ciliata | a green lacewing | 3 | 2014 |
| alder fly, lacewing or snake fly | Coniopterygidae | a dustywing (unidentified) | 2 | 2016 |
| alder fly, lacewing or snake fly | Coniopteryginae | a Coniopteryginae species (unidentified) | 1 | 2023 |
| alder fly, lacewing or snake fly | Coniopteryx (Coniopteryx) borealis | a white lacewing | 1 | 2015 |
| alder fly, lacewing or snake fly | Coniopteryx (Coniopteryx) tineiformis | a white lacewing | 1 | 1995 |
| alder fly, lacewing or snake fly | Cunctochrysa albolineata | an insect - lacewing (Neuroptera) | 2 | 2005 |
| algae or stonewort | Catenella caespitosa | an alga | 1 | 2025 |
| algae or stonewort | Caulacanthus okamurae | Pom-pom weed | 1 | 2025 |
| algae or stonewort | Ceramium deslongchampsii | an alga | 1 | 2025 |
| algae or stonewort | Chara | a Chara stonewort (unidentified) | 52 | 2013 |
| algae or stonewort | Chara aculeolata | Hedgehog stonewort | 4 | 2009 |
| algae or stonewort | Chara contraria | Opposite Stonewort | 9 | 2015 |
| algae or stonewort | Chara globularis sens. lat. | Fragile Stonewort | 18 | 2015 |
| algae or stonewort | Chara hispida sens. lat. | Bristly Stonewort | 7 | 2000 |
| algae or stonewort | Chara virgata | Delicate Stonewort | 4 | 2003 |
| algae or stonewort | Chara virgata var. virgata | a Delicate Stonewort | 1 | 1990 |
| algae or stonewort | Chara vulgaris | Common Stonewort | 34 | 2016 |
| algae or stonewort | Chara vulgaris var. longibracteata | Common Stonewort var. longibracteata | 3 | 1999 |
| algae or stonewort | Chara vulgaris var. papillata | Common Stonewort var. papillata | 1 | 1917 |
| algae or stonewort | Chara vulgaris var. vulgaris | Common Stonewort var. vulgaris | 2 | 2016 |
| algae or stonewort | Charophyta | charophytes | 3 | 2004 |
| algae or stonewort | Chlorophyta | Filamentous green algae | 2 | 2023 |
| algae or stonewort | Chlorophyta/Xanthophyta sp. | a Chlorophyta/Xanthophyta filamentous alga (unidentified) | 36 | 2000 |
| algae or stonewort | Chondrus crispus | Carragheen | 2 | 1971 |
| algae or stonewort | Cladophora | Blanket Weed | 15 | 2022 |
| algae or stonewort | Cladophora glomerata | an alga | 21 | 2014 |
| algae or stonewort | Cladophora rupestris | an alga | 3 | 2025 |
| algae or stonewort | Closterium | a Closterium species (unidentified) | 1 | 2010 |
| algae or stonewort | Corallina officinalis | Coral Weed | 5 | 1990 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Caenacis inflexa | a chalcid wasp | 1 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Calameuta filiformis | Reed Stem Borer | 6 | 2025 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Calameuta pallipes | Pale-legged Stem-sawfly | 6 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Caliadurgus fasciatellus | a spider-hunting wasp | 4 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Caliroa annulipes | Ring-footed Slugworm | 3 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Caliroa cerasi | Cherry Slugworm | 5 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Callajoppa cirrogaster | an ichneumon wasp | 1 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Callirhytis erythrocephala f. agamic | an insect - hymenopteran | 2 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Campoletis annulata | an insect - hymenopteran | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Campopleginae | a Campopleginae species (unidentified) | 1 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Campoplex eudoniae | an insect - hymenopteran | 3 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cecidostiba fungosa | an insect - hymenopteran | 26 | 2004 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cecidostiba semifascia | a chalcid wasp | 19 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cephus pygmeus | Wheat Stem Borer | 3 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cephus spinipes | Angled Stem-sawfly | 3 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Ceratina cyanea | Blue Carpenter Bee | 9 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cerceris arenaria | Sand Tailed Digger Wasp | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cerceris rybyensis | Ornate Tailed Digger Wasp | 21 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Ceroptres clavicornis | a gall wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chalcididae | a Chalcididae species (unidentified) | 15 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chalcis sispes | a thick-legged chalcid wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chelostoma campanularum | Harebell Carpenter Bee | 3 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chelostoma florisomne | Sleepy Carpenter Bee | 5 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysis | Ruby-tailed Wasp | 6 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysis angustula | a ruby-tailed wasp | 3 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysis ignita | a ruby-tailed wasp | 17 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysis ruddii | a ruby-tailed wasp | 1 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysis vanlithi | a ruby-tailed wasp | 1 | 1987 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Chrysura radians | a rubytail wasp | 1 | 1987 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cidaphus atricillus | an ichneumon wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cimbex femoratus | Birch Clubhorn | 4 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cimbex luteus | Willow Clubhorn | 1 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cirrospilus vittatus | a chalcid wasp | 1 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cladius brullei | Brulles Knucklehorn | 2 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cladius compressicornis | Compressed Knucklehorn | 1 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cladius pectinicornis | Stag Knucklehorn | 3 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Claremontia confusa | Strawberry Claremont | 3 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Claremontia tenuicornis | Slender-horned Claremont | 3 | 2004 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cleptes semiauratus | a rubytail wasp | 2 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Clinocentrus cunctator | a braconid wasp | 1 | 1995 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Clinocentrus exsertor | a braconid wasp | 2 | 1995 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Clistopyga incitator | an ichneumon wasp | 1 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Coelinidea niger | a braconid wasp | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Coelioxys | a Coelioxys species (unidentified) | 8 | 2022 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Coelioxys elongata | Dull-vented Sharp-tail Bee | 4 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Coelioxys inermis | Shiny-vented Sharp-tail Bee | 5 | 2022 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Coelopisthia extenta | a chalcid wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Colletes cunicularius | Vernal Colletes | 1 | 2022 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Colletes daviesanus | Davies' Colletes | 3 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Colletes hederae | Ivy Bee | 73 | 2024 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Colletes similis | Bare-saddled Colletes | 4 | 2015 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Colletes succinctus | Heather (Girdled) Colletes | 6 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cotesia glomerata | an insect - hymenopteran | 1 | 1979 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crabro cribrarius | Slender Bodied Digger Wasp | 2 | 2017 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus | a Crossocerus species (unidentified) | 3 | 2017 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus annulipes | a solitary wasp | 3 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus cetratus | a solitary wasp | 4 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus dimidiatus | Blunt Tailed Digger Wasp | 8 | 2015 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus distinguendus | a solitary wasp | 3 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus elongatulus | Slender Digger Wasp | 13 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus megacephalus | a solitary wasp | 13 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus nigritus | a solitary wasp | 6 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus ovalis | a solitary wasp | 2 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus podagricus | a solitary wasp | 7 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus quadrimaculatus | 4-spotted Digger Wasp | 4 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus styrius | a solitary wasp | 2 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus tarsatus | a solitary wasp | 1 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus vagabundus | a solitary wasp | 1 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus varus | a solitary wasp | 3 | 2024 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crossocerus walkeri | a solitary wasp | 1 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Crypteffigies lanius | an ichneumon wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cryptus armator | an insect - hymenopteran | 3 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cyclolabus nigricollis | an ichneumon wasp | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cynipidae | a gall wasp (unidentified) | 11 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cynips divisa | Red Currant Gall | 2 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cynips longiventris | a gall wasp | 4 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cynips longiventris f. agamic | Striped-pea Gall Causer | 6 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cynips quercusfolii | Cherry Gall | 2 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Cyrtogaster vulgaris | a chalcid wasp | 2 | 2003 |
| bacterium | Chroococcus | a Chroococcus species (unidentified) | 1 | 2010 |
| bacterium | Cyanophyta | Blue-green algal scum / pelts | 1 | 1998 |
| beetle | Caenoscelis ferruginea | a silken fungus beetle | 1 | 2015 |
| beetle | Cafius xantholoma | a rove beetle | 13 | 2019 |
| beetle | Calambus bipustulatus | a click beetle | 1 | 1932 |
| beetle | Calamosternus granarius | a dung beetle or chafer | 1 | 1994 |
| beetle | Calathus cinctus/melanocephalus agg. | a ground beetle | 3 | 2015 |
| beetle | Calathus fuscipes | a ground beetle | 21 | 2020 |
| beetle | Calathus melanocephalus | a ground beetle | 14 | 2020 |
| beetle | Calathus mollis | a ground beetle | 2 | 2019 |
| beetle | Calathus rotundicollis | a ground beetle | 38 | 2021 |
| beetle | Calodromius spilotus | a ground beetle | 16 | 2021 |
| beetle | Calosirus terminatus | a weevil | 3 | 1968 |
| beetle | Calvia quattuordecimguttata | Cream-spot ladybird | 152 | 2025 |
| beetle | Cantharidae | a soldier beetle (unidentified) | 18 | 2017 |
| beetle | Cantharis | a Cantharis species (unidentified) | 7 | 2018 |
| beetle | Cantharis cryptica | a soldier beetle | 26 | 2024 |
| beetle | Cantharis decipiens | a soldier beetle | 66 | 2024 |
| beetle | Cantharis figurata | a soldier beetle | 8 | 2024 |
| beetle | Cantharis flavilabris (=nigra auctt.) black scutellum | a soldier beetle | 74 | 2024 |
| beetle | Cantharis fusca | a soldier beetle | 14 | 2019 |
| beetle | Cantharis lateralis | a soldier beetle | 18 | 2017 |
| beetle | Cantharis livida | a soldier beetle | 28 | 2021 |
| beetle | Cantharis nigra (=thoracica) red scutellum | a soldier beetle | 1 | 1999 |
| beetle | Cantharis nigricans | a soldier beetle | 33 | 2023 |
| beetle | Cantharis pallida | a soldier beetle | 14 | 2018 |
| beetle | Cantharis pellucida | a soldier beetle | 18 | 2021 |
| beetle | Cantharis rufa | a soldier beetle | 33 | 2023 |
| beetle | Cantharis rustica | a soldier beetle | 165 | 2023 |
| beetle | Carabidae | Ground beetle | 19 | 2023 |
| beetle | Carabus | a Carabus species (unidentified) | 2 | 2014 |
| beetle | Carabus granulatus | Granulated Ground Beetle | 27 | 2023 |
| beetle | Carabus monilis | Necklace Ground Beetle | 6 | 2018 |
| beetle | Carabus nemoralis | a ground beetle | 1 | 1999 |
| beetle | Carabus problematicus | Rough Violet Ground Beetle | 34 | 2021 |
| beetle | Carabus violaceus | Violet Ground Beetle | 57 | 2023 |
| beetle | Carpelimus | a Carpelimus species (unidentified) | 2 | 2022 |
| beetle | Carpelimus bilineatus/erichsoni agg. | a rove beetle | 1 | 1998 |
| beetle | Carpelimus elongatulus | a rove beetle | 3 | 2022 |
| beetle | Carpophilus marginellus | a pollen or sap beetle | 2 | 2017 |
| beetle | Cartodere bifasciata | a mould beetle | 11 | 2023 |
| beetle | Cartodere nodifer | a mould beetle | 50 | 2021 |
| beetle | Cassida flaveola | Pale Tortoise Beetle | 1 | 2001 |
| beetle | Cassida murraea | Fleabane Tortoise Beetle | 13 | 2023 |
| beetle | Cassida rubiginosa | Thistle Tortoise Beetle | 35 | 2023 |
| beetle | Cassida vibex | a leaf beetle | 15 | 2024 |
| beetle | Cassida viridis | Green Tortoise Beetle | 21 | 2024 |
| beetle | Cassida vittata | Borded Tortoise Beetle | 6 | 2019 |
| beetle | Catapion pubescens | a seed weevil | 1 | 1998 |
| beetle | Catapion seniculus | a seed weevil | 10 | 2010 |
| beetle | Cathormiocerus spinosus | a weevil | 4 | 1968 |
| beetle | Catops | a Catops species (unidentified) | 12 | 2020 |
| beetle | Catops chrysomeloides | a round fungus beetle | 5 | 2003 |
| beetle | Catops fuliginosus | a round fungus beetle | 56 | 2021 |
| beetle | Catops fuscus | a round fungus beetle | 8 | 2016 |
| beetle | Catops grandicollis | a round fungus beetle | 2 | 2015 |
| beetle | Catops kirbyi | a round fungus beetle | 1 | 1978 |
| beetle | Catops morio | a round fungus beetle | 3 | 2021 |
| beetle | Catops nigricans | a round fungus beetle | 30 | 2021 |
| beetle | Catops tristis | a round fungus beetle | 28 | 2022 |
| beetle | Cephennium gallicum | a small ant-like beetle | 1 | 2008 |
| beetle | Cerambycidae | Longhorn Beetle | 1 | 2011 |
| beetle | Cerambycidae sp. or Nitidulidae sp. | a longhorn beetle (unidentified Cerambycidae sp. or Nitidulidae sp.) | 5 | 2012 |
| beetle | Ceratapion | a Ceratapion species (unidentified) | 1 | 1986 |
| beetle | Ceratapion carduorum | a seed weevil | 6 | 2023 |
| beetle | Ceratapion gibbirostre | a seed weevil | 11 | 2023 |
| beetle | Ceratapion onopordi | a seed weevil | 15 | 2017 |
| beetle | Cercyon | a Cercyon species (unidentified) | 2 | 2012 |
| beetle | Cercyon analis | a scavenger water beetle | 4 | 2017 |
| beetle | Cercyon bifenestratus | a scavenger water beetle | 1 | 2021 |
| beetle | Cercyon convexiusculus | a scavenger water beetle | 9 | 2012 |
| beetle | Cercyon depressus | a scavenger water beetle | 2 | 2017 |
| beetle | Cercyon haemorrhoidalis | a scavenger water beetle | 3 | 2021 |
| beetle | Cercyon impressus | a scavenger water beetle | 1 | 2009 |
| beetle | Cercyon laminatus | a scavenger water beetle | 2 | 2014 |
| beetle | Cercyon lateralis | a scavenger water beetle | 4 | 2022 |
| beetle | Cercyon littoralis | a scavenger water beetle | 6 | 2021 |
| beetle | Cercyon marinus | a scavenger water beetle | 3 | 2002 |
| beetle | Cercyon melanocephalus | a scavenger water beetle | 2 | 2016 |
| beetle | Cercyon obsoletus | an insect - beetle (Coleoptera) | 1 | 2002 |
| beetle | Cercyon pygmaeus | a scavenger water beetle | 5 | 2023 |
| beetle | Cercyon quisquilius | a scavenger water beetle | 7 | 2023 |
| beetle | Cercyon sternalis | a scavenger water beetle | 1 | 1999 |
| beetle | Cercyon terminatus | a scavenger water beetle | 2 | 1997 |
| beetle | Cercyon tristis | a scavenger water beetle | 3 | 1999 |
| beetle | Cercyon unipunctatus | a scavenger water beetle | 3 | 2023 |
| beetle | Cerylon ferrugineum | a cerylonid beetle | 5 | 2016 |
| beetle | Cerylon histeroides | a cerylonid beetle | 6 | 2021 |
| beetle | Cetonia aurata | Rose Chafer | 935 | 2025 |
| beetle | Ceutorhynchus | a Ceutorhynchus species (unidentified) | 2 | 2015 |
| beetle | Ceutorhynchus alliariae | a weevil | 1 | 1979 |
| beetle | Ceutorhynchus assimilis sens. lat. (assimilis/obstrictus) | Cabbage Gall Weevil | 6 | 2003 |
| beetle | Ceutorhynchus cochleariae | a weevil | 1 | 1983 |
| beetle | Ceutorhynchus contractus | Cabbage Leaf Weevil | 5 | 2015 |
| beetle | Ceutorhynchus erysimi | a weevil | 6 | 2008 |
| beetle | Ceutorhynchus hirtulus | a weevil | 2 | 2018 |
| beetle | Ceutorhynchus obstrictus (=assimilis auctt.) | Cabbage Seed Weevil | 25 | 2023 |
| beetle | Ceutorhynchus pallidactylus | Cabbage Stem Weevil | 18 | 2020 |
| beetle | Ceutorhynchus pyrrhorhynchus | a weevil | 3 | 1978 |
| beetle | Ceutorhynchus typhae | a weevil | 5 | 2016 |
| beetle | Chaetocnema | a Chaetocnema species (unidentified) | 1 | 2020 |
| beetle | Chaetocnema concinna | Beet Flea Beetle | 31 | 2023 |
| beetle | Chaetocnema confusa | a leaf beetle | 3 | 2015 |
| beetle | Chaetocnema hortensis | a leaf beetle | 24 | 2023 |
| beetle | Chaetocnema picipes | a leaf beetle | 3 | 2023 |
| beetle | Chaetocnema sahlbergii | a leaf beetle | 5 | 2019 |
| beetle | Charagmus griseus | a weevil | 2 | 2019 |
| beetle | Chilocorus bipustulatus | Heather Ladybird | 2 | 2021 |
| beetle | Chilocorus renipustulatus | Kidney-spot Ladybird | 18 | 2020 |
| beetle | Chilothorax distinctus | a dung beetle or chafer | 2 | 2019 |
| beetle | Chlaenius nigricornis | a ground beetle | 2 | 2015 |
| beetle | Choleva agilis | a round fungus beetle | 14 | 2021 |
| beetle | Choleva fagniezi | a round fungus beetle | 1 | 1999 |
| beetle | Chrysolina | a Chrysolina species (unidentified) | 2 | 2023 |
| beetle | Chrysolina americana | Rosemary Beetle | 75 | 2024 |
| beetle | Chrysolina banksii | a leaf beetle | 1 | 2019 |
| beetle | Chrysolina fastuosa | Dead-nettle Leaf Beetle | 1 | 2021 |
| beetle | Chrysolina herbacea | Mint Leaf Beetle | 11 | 2021 |
| beetle | Chrysolina hyperici | a leaf beetle | 11 | 2024 |
| beetle | Chrysolina oricalcia | a leaf beetle | 13 | 2023 |
| beetle | Chrysolina polita | Knotgrass Leaf Beetle | 30 | 2024 |
| beetle | Chrysolina staphylaea | a leaf beetle | 35 | 2024 |
| beetle | Chrysolina sturmi | a leaf beetle | 3 | 2000 |
| beetle | Chrysolina varians | a leaf beetle | 3 | 2014 |
| beetle | Chrysomela | a Chrysomela species (unidentified) | 2 | 2013 |
| beetle | Chrysomela populi | Red Poplar Leaf Beetle | 2 | 2016 |
| beetle | Chrysomelidae | indet leaf beetle (unidentified) | 19 | 2023 |
| beetle | Cicindela campestris | Green Tiger Beetle | 23 | 2023 |
| beetle | Cilea silphoides | a rove beetle | 2 | 2014 |
| beetle | Cionus alauda | a weevil | 5 | 2024 |
| beetle | Cionus hortulanus | a weevil | 6 | 2022 |
| beetle | Cionus scrophulariae | Figwort Weevil | 53 | 2022 |
| beetle | Cionus tuberculosus | a weevil | 11 | 2024 |
| beetle | Cis bidentatus | a small fungus beetle | 1 | 2020 |
| beetle | Cis bilamellatus | a small fungus beetle | 30 | 2023 |
| beetle | Cis boleti | a small fungus beetle | 14 | 2021 |
| beetle | Cis castaneus | a small fungus beetle | 6 | 2016 |
| beetle | Cis fagi | a small fungus beetle | 7 | 2021 |
| beetle | Cis festivus | a small fungus beetle | 3 | 2020 |
| beetle | Cis micans | a small fungus beetle | 1 | 2021 |
| beetle | Clambus armadillo | an armadillo beetle | 1 | 1990 |
| beetle | Clitostethus arcuatus | a ladybird | 2 | 2023 |
| beetle | Clivina collaris | a ground beetle | 1 | 1967 |
| beetle | Clivina fossor | a ground beetle | 32 | 2021 |
| beetle | Clytra quadripunctata | a leaf beetle | 1 | 2003 |
| beetle | Clytus arietis | Wasp Beetle | 84 | 2024 |
| beetle | Coccidula rufa | a ladybird | 60 | 2023 |
| beetle | Coccidula scutellata | a ladybird | 6 | 2009 |
| beetle | Coccinella quinquepunctata | Five-spot Ladybird | 2 | 2024 |
| beetle | Coccinella septempunctata | Seven-spot Ladybird | 1809 | 2025 |
| beetle | Coccinella undecimpunctata | 11-spot Ladybird | 21 | 2023 |
| beetle | Coccinellidae | Indet. Ladybird | 176 | 2023 |
| beetle | Coccinellinae | a Coccinellinae ladybird (unidentified) | 1 | 2023 |
| beetle | Coeliodes rana | a weevil | 7 | 2020 |
| beetle | Coeliodinus rubicundus | a weevil | 1 | 2023 |
| beetle | Coelositona cambricus | a weevil | 1 | 2017 |
| beetle | Coelostoma orbiculare | a scavenger water beetle | 11 | 2023 |
| beetle | Coleoptera | Beetle | 125 | 2023 |
| beetle | Colymbetes fuscus | a water beetle | 76 | 2021 |
| beetle | Colymbetinae | a Colymbetinae species (unidentified) | 8 | 2013 |
| beetle | Conopalpus testaceus | a false darkling beetle | 1 | 2001 |
| beetle | Contacyphon coarctatus | a marsh beetle | 40 | 2023 |
| beetle | Contacyphon laevipennis | a marsh beetle | 3 | 2009 |
| beetle | Contacyphon ochraceus | a marsh beetle | 9 | 2018 |
| beetle | Contacyphon padi | a marsh beetle | 2 | 2015 |
| beetle | Contacyphon palustris | a marsh beetle | 1 | 2009 |
| beetle | Contacyphon variabilis | a marsh beetle | 5 | 2015 |
| beetle | Coprophilus striatulus | a rove beetle | 1 | 1982 |
| beetle | Cordalia obscura | a rove beetle | 1 | 2021 |
| beetle | Corticaria crenulata | a mould beetle | 4 | 2021 |
| beetle | Corticaria impressa | a mould beetle | 7 | 2023 |
| beetle | Corticaria umbilicata | a mould beetle | 1 | 2016 |
| beetle | Corticarina minuta | a mould beetle | 6 | 2023 |
| beetle | Cortinicara gibbosa | a mould beetle | 50 | 2023 |
| beetle | Creophilus maxillosus | Hairy Rove Beetle | 4 | 2019 |
| beetle | Crepidodera | a Chalcoides species (unidentified) | 3 | 2023 |
| beetle | Crepidodera aurata | Willow Flea Beetle | 41 | 2023 |
| beetle | Crepidodera aurea | a leaf beetle | 31 | 2023 |
| beetle | Crepidodera fulvicornis | a leaf beetle | 10 | 2021 |
| beetle | Crepidodera plutus | an insect - beetle (Coleoptera) | 39 | 2023 |
| beetle | Crioceris asparagi | Asparagus Beetle | 3 | 2022 |
| beetle | Cryptarcha strigata | a pollen or sap beetle | 6 | 2018 |
| beetle | Cryptocephalus | Leaf beetle | 2 | 2023 |
| beetle | Cryptocephalus aureolus | a leaf beetle | 31 | 2023 |
| beetle | Cryptocephalus bipunctatus | a leaf beetle | 16 | 2024 |
| beetle | Cryptocephalus fulvus | a leaf beetle | 4 | 2019 |
| beetle | Cryptocephalus hypochaeridis | a leaf beetle | 3 | 2021 |
| beetle | Cryptocephalus labiatus | a leaf beetle | 10 | 2020 |
| beetle | Cryptocephalus moraei | a leaf beetle | 21 | 2024 |
| beetle | Cryptocephalus pusillus | a leaf beetle | 15 | 2023 |
| beetle | Cryptolaemus montrouzieri | a ladybird | 1 | 2014 |
| beetle | Cryptophagus dentatus | a silken fungus beetle | 9 | 2016 |
| beetle | Cryptophagus laticollis | a silken fungus beetle | 1 | 1999 |
| beetle | Cryptophagus pubescens | a silken fungus beetle | 1 | 2016 |
| beetle | Cryptophagus ruficornis | a silken fungus beetle | 1 | 2015 |
| beetle | Cryptophagus scanicus | a silken fungus beetle | 38 | 2023 |
| beetle | Cryptophagus setulosus | a silken fungus beetle | 1 | 1969 |
| beetle | Cryptopleurum minutum | a scavenger water beetle | 3 | 2022 |
| beetle | Cryptopleurum subtile | a scavenger water beetle | 1 | 1997 |
| beetle | Cryptorhynchus lapathi | Withy weevil | 1 | 2015 |
| beetle | Crypturgus cinereus | a weevil | 1 | 2015 |
| beetle | Ctenicera cuprea | a click beetle | 1 | 2019 |
| beetle | Cteniopus sulphureus | Sulphur Beetle | 33 | 2023 |
| beetle | Ctesias serra | Cobweb Beetle | 6 | 2023 |
| beetle | Curculio | a Curculio species (unidentified) | 1 | 2023 |
| beetle | Curculio glandium | Acorn Weevil | 47 | 2024 |
| beetle | Curculionidae | a weevil | 24 | 2018 |
| beetle | Curculio nucum | Nut Weevil | 12 | 2023 |
| beetle | Curculio venosus | a weevil | 12 | 2024 |
| beetle | Curculio villosus | a weevil | 2 | 2020 |
| beetle | Curimopsis maritima | a pill beetle | 2 | 1938 |
| beetle | Curtonotus aulicus | a ground beetle | 12 | 2023 |
| beetle | Curtonotus convexiusculus | a ground beetle | 1 | 2019 |
| beetle | Cyanapion afer | a seed weevil | 11 | 2010 |
| beetle | Cychramus luteus | a pollen or sap beetle | 2 | 2015 |
| beetle | Cychrus caraboides | Snail Hunter | 20 | 2021 |
| beetle | Cymbiodyta marginella | a scavenger water beetle | 44 | 2022 |
| beetle | Cypha longicornis | a rove beetle | 11 | 2023 |
| beetle | Cytilus sericeus | a pill beetle | 5 | 2022 |
| bird | Cairina moschata | Muscovy duck | 80 | 2018 |
| bird | Calcarius lapponicus | Lapland Bunting | 32 | 2021 |
| bird | Calidris | a Calidris species (unidentified) | 1 | 2019 |
| bird | Calidris alba | Sanderling | 1060 | 2024 |
| bird | Calidris alpina | Dunlin | 15297 | 2024 |
| bird | Calidris alpina arctica | Arctica Dunlin | 10 | 2021 |
| bird | Calidris alpina schinzii | schinzii Dunlin | 1 | 2018 |
| bird | Calidris bairdii | Baird's Sandpiper | 2 | 2001 |
| bird | Calidris canutus | Knot | 2882 | 2024 |
| bird | Calidris ferruginea | Curlew Sandpiper | 2003 | 2022 |
| bird | Calidris fuscicollis | White-rumped Sandpiper | 2 | 2001 |
| bird | Calidris maritima | Purple Sandpiper | 684 | 2024 |
| bird | Calidris melanotos | Pectoral Sandpiper | 213 | 2022 |
| bird | Calidris minuta | Little Stint | 1553 | 2022 |
| bird | Calidris pugnax | Ruff | 2363 | 2022 |
| bird | Calidris pusilla | Semipalmated Sandpiper | 1 | 2009 |
| bird | Calidris subruficollis | Buff-breasted Sandpiper | 1 | 1986 |
| bird | Calidris temminckii | Temminck's Stint | 54 | 2019 |
| bird | Calonectris diomedea | Cory's Shearwater | 1 | 2000 |
| bird | Caprimulgus europaeus | Nightjar | 104 | 2022 |
| bird | Carduelis | a Carduelis species (unidentified) | 3 | 2009 |
| bird | Carduelis carduelis | Goldfinch | 45025 | 2025 |
| bird | Carpodacus erythrinus | Common Rosefinch | 5 | 2017 |
| bird | Cayuga Duck | Cayuga Duck | 1 | 2023 |
| bird | Cecropis daurica | Red-rumped Swallow | 5 | 2022 |
| bird | Cepphus grylle | Black Guillemot | 4 | 2015 |
| bird | Certhia familiaris | Treecreeper | 6116 | 2025 |
| bird | Cettia cetti | Cetti's Warbler | 10673 | 2025 |
| bird | Charadriidae | Plovers | 2 | 2016 |
| bird | Charadrius dubius | Little Ringed Plover | 3344 | 2022 |
| bird | Charadrius hiaticula | Ringed Plover | 7881 | 2024 |
| bird | Charadrius vociferus | Killdeer | 1 | 1986 |
| bird | Chlidonias hybrida | Whiskered Tern | 17 | 2016 |
| bird | Chlidonias leucopterus | White-winged Black Tern | 22 | 2014 |
| bird | Chlidonias niger | Black Tern | 1073 | 2022 |
| bird | Chlidonias niger surinamensis | American Black Tern | 3 | 1999 |
| bird | Chloris chloris | Greenfinch | 33749 | 2025 |
| bird | Chroicocephalus philadelphia | Bonaparte's Gull | 7 | 2017 |
| bird | Chroicocephalus ridibundus | Black-headed Gull | 26642 | 2025 |
| bird | Chrysolophus pictus | Golden Pheasant | 6 | 2019 |
| bird | Ciconia ciconia | White Stork | 48 | 2021 |
| bird | Cinclus cinclus | Dipper | 3492 | 2025 |
| bird | Circus | Indet. Harrier | 11 | 2021 |
| bird | Circus aeruginosus | Marsh Harrier | 3122 | 2025 |
| bird | Circus cyaneus | Hen Harrier | 265 | 2022 |
| bird | Circus macrourus | Pallid Harrier | 1 | 2016 |
| bird | Circus pygargus | Montagu's Harrier | 35 | 2015 |
| bird | Clangula hyemalis | Long-tailed Duck | 1338 | 2023 |
| bird | Coccothraustes coccothraustes | Hawfinch | 894 | 2024 |
| bird | Coloeus monedula | Jackdaw | 36892 | 2025 |
| bird | Coloeus monedula monedula | Nordic Jackdaw | 2 | 2019 |
| bird | Columba | Pigeon | 79 | 2025 |
| bird | Columba livia | Feral Pigeon/Rock Dove | 30456 | 2025 |
| bird | Columba oenas | Stock Dove | 10196 | 2025 |
| bird | Columba palumbus | Woodpigeon | 70980 | 2025 |
| bird | Columba sp. or Streptopelia sp. (a pigeon or dove unidentified) | a pigeon or dove (unidentified) | 210 | 2021 |
| bird | Columbidae | Doves, pigeons | 3 | 2024 |
| bird | Corvidae | Crows | 110 | 2024 |
| bird | Corvus | Corvid Species | 123 | 2023 |
| bird | Corvus corax | Raven | 21353 | 2025 |
| bird | Corvus corone | Carrion Crow | 52705 | 2025 |
| bird | Corvus corone agg. | Carrion Crow/Hooded Crow | 1 | 2018 |
| bird | Corvus frugilegus | Rook | 18147 | 2025 |
| bird | Coturnix coturnix | Quail | 254 | 2022 |
| bird | Crex crex | Corncrake | 2 | 1986 |
| bird | Cuculus canorus | Cuckoo | 6388 | 2025 |
| bird | Curruca communis | Whitethroat | 11770 | 2025 |
| bird | Curruca curruca | Lesser Whitethroat | 5123 | 2025 |
| bird | Curruca undata | Dartford Warbler | 156 | 2022 |
| bird | Cyanistes caeruleus | Blue Tit | 69726 | 2025 |
| bird | Cygnus | Swan | 37 | 2022 |
| bird | Cygnus atratus | Black Swan | 168 | 2024 |
| bird | Cygnus columbianus | Bewick's Swan | 1159 | 2022 |
| bird | Cygnus cygnus | Whooper Swan | 193 | 2022 |
| bird | Cygnus melancoryphus | Black-necked Swan | 1 | 2008 |
| bird | Cygnus olor | Mute Swan | 20905 | 2025 |
| booklouse or barklouse | Cerobasis guestfalica | a booklouse or barklouse | 4 | 1995 |
| bryozoan | Conopeum reticulum | an encrusting bryozoan | 1 | 1997 |
| bryozoan | Cryptosula pallasiana | a bryozoan | 1 | 1937 |
| bug | Cacopsylla ambigua | a jumping plantlouse | 1 | 2009 |
| bug | Cacopsylla fulguralis | Eleagnus Sucker | 1 | 2023 |
| bug | Cacopsylla melanoneura | a jumping plantlouse | 5 | 2023 |
| bug | Cacopsylla peregrina | a jumping plantlouse | 2 | 2015 |
| bug | Cacopsylla pyricola | a jumping plantlouse | 1 | 2020 |
| bug | Callicorixa praeusta | a waterboatman | 21 | 2023 |
| bug | Calocoris | a Calocoris species (unidentified) | 1 | 2014 |
| bug | Calocoris (Calocoris) alpestris | a plantbug or grassbug | 9 | 2023 |
| bug | Calocoris (Calocoris) roseomaculatus | a plantbug or grassbug | 6 | 2012 |
| bug | Campyloneura virgula | a plantbug or grassbug | 44 | 2025 |
| bug | Campylosteira verna | a lace bug | 1 | 2018 |
| bug | Capsodes gothicus | a plantbug or grassbug | 1 | 1987 |
| bug | Capsus ater | a plantbug or grassbug | 105 | 2024 |
| bug | Cardiastethus fasciiventris | a flower bug or bloodsucking bug | 5 | 2021 |
| bug | Cavariella (Cavariella) aegopodii | Willow-Carrot Aphid | 22 | 1985 |
| bug | Centrotus cornutus | Tree Hopper | 47 | 2023 |
| bug | Ceraleptus lividus | Slender-horned Leatherbug | 1 | 2019 |
| bug | Cercopidae | Froghopper | 12 | 2021 |
| bug | Cercopis vulnerata | Red-and-black Froghopper | 165 | 2025 |
| bug | Chaetosiphon (Pentatrichopus) fragaefolii | Strawberry Aphid | 5 | 1975 |
| bug | Charagochilus (Charagochilus) gyllenhalii | a plantbug or grassbug | 2 | 2022 |
| bug | Chartoscirta cincta | a shore bug | 9 | 2016 |
| bug | Chartoscirta cocksii | a shore bug | 7 | 2015 |
| bug | Chilacis typhae | a ground bug | 6 | 2025 |
| bug | Chloriona dorsata | a planthopper | 4 | 2009 |
| bug | Chloriona glaucescens | a planthopper | 5 | 2019 |
| bug | Chloriona unicolor | a planthopper | 5 | 2009 |
| bug | Cicadella viridis | a leafhopper | 74 | 2024 |
| bug | Cicadellidae | Leafhopper | 12 | 2023 |
| bug | Cicadula persimilis | a leafhopper | 6 | 2009 |
| bug | Cicadula quadrinotata | a leafhopper | 3 | 2009 |
| bug | Cimex lectularius | Bedbug | 1 | 1900 |
| bug | Cimex pipistrelli | Batbug | 3 | 2018 |
| bug | Cinara sp. | a hairy conifer aphid (unidentified) | 8 | 1975 |
| bug | Cixius distinguendus | a lacehopper | 2 | 2001 |
| bug | Cixius nervosus | a lacehopper | 18 | 2022 |
| bug | Cixius remotus | a lacehopper | 1 | 2001 |
| bug | Closterotomus fulvomaculatus | a plantbug or grassbug | 4 | 2011 |
| bug | Closterotomus norwegicus | Potato Capsid | 117 | 2025 |
| bug | Closterotomus trivialis | a plantbug or grassbug | 4 | 2024 |
| bug | Coccoidea sp. | a scale insect (unidentified) | 1 | 2012 |
| bug | Coccus hesperidum | Brown Soft-scale | 4 | 2017 |
| bug | Compsidolon (Coniortodes) salicellum | a plantbug or grassbug | 6 | 2025 |
| bug | Conomelus anceps | a planthopper | 18 | 2021 |
| bug | Conosanus obsoletus | a leafhopper | 3 | 2020 |
| bug | Coranus (Coranus) subapterus | Heath Assassin Bug | 1 | 1957 |
| bug | Coreidae | a Coreidae species (unidentified) | 1 | 2014 |
| bug | Coreus marginatus | Dock Bug | 639 | 2025 |
| bug | Coriomeris denticulatus | a squashbug | 38 | 2023 |
| bug | Corixa | a Corixa waterboatman (unidentified) | 91 | 2018 |
| bug | Corixa affinis | a waterboatman | 1 | 1992 |
| bug | Corixa dentipes | a waterboatman | 1 | 2013 |
| bug | Corixa panzeri | a waterboatman | 4 | 2012 |
| bug | Corixa punctata | Punctate Corixa | 101 | 2023 |
| bug | Corixidae | Lesser Water-Boatman | 61 | 2021 |
| bug | Corixidae sp. or Notonectidae sp. or Pleidae sp. (unidentified) | a waterboatman or water-boatman or backswimmer (unidentified) | 39 | 2018 |
| bug | Corixini | a Corixini false water-boatman (unidentified) | 1 | 2023 |
| bug | Corizus hyoscyami | a bug | 103 | 2024 |
| bug | Cryptomyzus (Cryptomyzus) ribis | an aphid | 2 | 2022 |
| bug | Cyllecoris histrionius | a plantbug or grassbug | 32 | 2023 |
| bug | Cymatia coleoptrata | a waterboatman | 5 | 2023 |
| bug | Cymus claviculus | a stiltbug | 1 | 2009 |
| bug | Cymus glandicolor | a stiltbug | 23 | 2024 |
| bug | Cymus melanocephalus | a stiltbug | 25 | 2023 |
| bug | Cyphostethus tristriatus | Juniper Shieldbug | 30 | 2023 |
| caddis fly | Ceraclea | a Ceraclea caddisfly (unidentified) | 1 | 2018 |
| caddis fly | Ceraclea dissimilis | a caddisfly | 2 | 2014 |
| caddis fly | Ceraclea fulva | a caddisfly | 1 | 1995 |
| caddis fly | Ceraclea senilis | a caddisfly | 1 | 2012 |
| caddis fly | Chaetopteryx villosa | a caddisfly | 12 | 2019 |
| caddis fly | Crunoecia irrorata | a caddisfly | 1 | 2001 |
| caddis fly | Cyrnus | a Cyrnus species (unidentified) | 1 | 1991 |
| caddis fly | Cyrnus trimaculatus | a caddisfly | 1 | 2013 |
| centipede | Chilopoda | Centipede | 32 | 2016 |
| centipede | Cryptops | a Cryptops species (unidentified) | 13 | 2023 |
| centipede | Cryptops hortensis | Common cryptops | 10 | 2011 |
| centipede | Cryptops parisi | Paris cryptops | 6 | 2013 |
| cockroach | Capraiellus panzeri | Lesser Cockroach | 1 | 1938 |
| crustacean | Calliopius laeviusculus | a crustacean | 1 | 1939 |
| crustacean | Cancer pagurus | Edible Crab | 2 | 2003 |
| crustacean | Carcinus maenas | Green Shore Crab | 23 | 2025 |
| crustacean | Chelura terebrans | a crustacean | 1 | 1939 |
| crustacean | Chirocephalus diaphanus | Fairy Shrimp | 2 | 2013 |
| crustacean | Corophium volutator | a crustacean | 3 | 1939 |
| crustacean | Crangon crangon | Brown Shrimp | 10 | 2016 |
| crustacean | Crangonyx pseudogracilis/floridanus sens. lat. | Northern River Crangonyctid | 254 | 2016 |
| crustacean | Crinocheta | a Crinocheta species (unidentified) | 1 | 2023 |
| crustacean | Cumopsis goodsir | a crustacean | 1 | 1976 |
| crustacean | Cyclopidae | a Cyclopidae species (unidentified) | 2 | 2020 |
| crustacean | Cyclopoida | a Cyclopoida species (unidentified) | 2 | 2010 |
| crustacean | Cyclops | a Cyclops species (unidentified) | 8 | 2012 |
| crustacean | Cypris | a Cypris species (unidentified) | 1 | 2010 |
| diatom | Caloneis fasciata | a diatom | 2 | 2016 |
| diatom | Centric diatoms | a diatom | 1 | 2015 |
| diatom | Cocconeis placentula | a diatom | 1 | 2015 |
| diatom | Cocconeis placentula var. euglypta | a diatom | 2 | 2015 |
| diatom | Cocconeis placentula var. lineata | a diatom | 1 | 2015 |
| diatom | Cyclotella | a Cyclotella diatom species (unidentified) | 1 | 2003 |
| dragonfly, hawker or damselfly | Calopterygidae | a Calopterygidae species (unidentified) | 2 | 2020 |
| dragonfly, hawker or damselfly | Calopteryx | Demoiselle damselflies | 12 | 2018 |
| dragonfly, hawker or damselfly | Calopteryx splendens | Banded Demoiselle | 1693 | 2025 |
| dragonfly, hawker or damselfly | Calopteryx virgo | Beautiful Demoiselle | 1388 | 2025 |
| dragonfly, hawker or damselfly | Chalcolestes viridis | Green Emerald Damselfly | 6 | 2025 |
| dragonfly, hawker or damselfly | Coenagrion | a Coenagrion species (unidentified) | 15 | 2012 |
| dragonfly, hawker or damselfly | Coenagrionidae | a Coenagrionidae damselfly (unidentified) | 58 | 2023 |
| dragonfly, hawker or damselfly | Coenagrion puella | Azure Damselfly | 3621 | 2025 |
| dragonfly, hawker or damselfly | Coenagrion pulchellum | Variable Damselfly | 142 | 2025 |
| dragonfly, hawker or damselfly | Cordulegaster boltonii | Golden-ringed Dragonfly | 31 | 2023 |
| dragonfly, hawker or damselfly | Cordulia aenea | Downy Emerald | 7 | 1989 |
| false scorpion | Chernes cimicoides | Common Tree-chernes | 1 | 2001 |
| false scorpion | Chthonius | a false scorpion (unidentified) | 1 | 2019 |
| false scorpion | Chthonius (Chthonius) | a false scorpion (Pseudoscorpiones) | 1 | 2009 |
| false scorpion | Chthonius ischnocheles | Common Chthonid | 3 | 2022 |
| false scorpion | Chthonius orthodactylus sens.str. | Straight-fingered Chthonid | 1 | 2013 |
| fish | Callionymus lyra | Dragonet | 4 | 1999 |
| fish | Callionymus reticulatus | Reticulated Dragonet | 1 | 1999 |
| fish | Capros aper | Boarfish | 1 | 1940 |
| fish | Carassius auratus | Goldfish | 22 | 2018 |
| fish | Carassius carassius | Crucian Carp | 3 | 1999 |
| fish | Centrolabrus exoletus | Rock Cook | 2 | 1999 |
| fish | Chelidonichthys cuculus | Red Gurnard | 4 | 1999 |
| fish | Chelidonichthys lastoviza | Streaked Gurnard | 2 | 1999 |
| fish | Chelidonichthys lucerna | Tub Gurnard | 3 | 1999 |
| fish | Chelon labrosus | Thick-lipped Mullet | 7 | 2025 |
| fish | Ciliata mustela | Five-bearded Rockling | 4 | 2009 |
| fish | Ciliata septentrionalis | Northern Rockling | 1 | 1999 |
| fish | Clupea harengus | Herring | 5 | 1999 |
| fish | Conger conger | Conger Eel | 9 | 2021 |
| fish | Cottidae | a Cottidae species (unidentified) | 1 | 2000 |
| fish | Cottus perifretum | Bullhead | 233 | 2025 |
| fish | Crystallogobius linearis | Crystal Goby | 1 | 1999 |
| fish | Ctenolabrus rupestris | Goldsinny | 1 | 1999 |
| fish | Cyclopterus lumpus | Lumpsucker | 6 | 1999 |
| fish | Cyprinus | a Cyprinus species (unidentified) | 1 | 1988 |
| fish | Cyprinus carpio | Carp | 27 | 2023 |
| flea | Ceratophyllus (Ceratophyllus) farreni subsp. farreni | a bird flea | 1 | 1924 |
| flea | Ceratophyllus (Ceratophyllus) gallinae | hen flea | 2 | 1976 |
| flea | Ceratophyllus (Emmareus) columbae | pigeon flea | 2 | 1951 |
| flea | Ctenocephalides canis | dog flea | 1 | 1954 |
| flea | Ctenocephalides felis subsp. felis | cat flea | 2 | 2002 |
| fungus | Calcarisporium arbuscula | a fungus | 1 | 2014 |
| fungus | Calloria tremelloides | Nettle Pox | 18 | 2013 |
| fungus | Caloboletus radicans | Rooting Bolete | 13 | 2011 |
| fungus | Calocera cornea | Small Stagshorn | 56 | 2023 |
| fungus | Calocera pallidospathulata | Pale Stagshorn | 4 | 2012 |
| fungus | Calocera viscosa | Yellow Stagshorn | 67 | 2022 |
| fungus | Calocybe gambosa | St. George's Mushroom | 150 | 2023 |
| fungus | Calvatia gigantea | Giant Puffball | 35 | 2023 |
| fungus | Calycina citrina | Lemon Disco | 69 | 2021 |
| fungus | Calycina claroflava | Sulphur Disco | 11 | 2010 |
| fungus | Calycina discreta | an ascomycete fungus | 1 | 1997 |
| fungus | Calycina herbarum | an ascomycete fungus | 5 | 2010 |
| fungus | Calyptella campanula | Bell Hoodie | 3 | 2008 |
| fungus | Calyptella capula | Bowl Hoodie | 13 | 2023 |
| fungus | Camarosporium tiliae | a fungus | 1 | 2013 |
| fungus | Candelabrum spinulosum | a fungus | 1 | 2012 |
| fungus | Cantharellus cibarius | Chanterelle | 4 | 2012 |
| fungus | Cantharellus tubaeformis | Trumpet Chanterelle | 3 | 2012 |
| fungus | Cercidospora epipolytropa | a fungus | 2 | 2004 |
| fungus | Cercospora scandens | a fungus | 1 | 2014 |
| fungus | Cercosporella lindaviana | a fungus | 1 | 1999 |
| fungus | Ceriporia purpurea | Bruising Porecrust | 1 | 2012 |
| fungus | Ceriporia reticulata | Reticulate Porecrust | 8 | 2013 |
| fungus | Ceriporia viridans | Greening Porecrust | 5 | 2014 |
| fungus | Ceriporiopsis pannocincta | Green Porecrust | 1 | 2008 |
| fungus | Cerrena unicolor | Labyrinth Turkeytail | 3 | 2013 |
| fungus | Chaetosphaerella phaeostroma | Black Velvet | 52 | 2020 |
| fungus | Chalciporus piperatus | Peppery Bolete | 10 | 2021 |
| fungus | Chamaemyces fracidus | Dewdrop Dapperling | 3 | 2008 |
| fungus | Cheilymenia | a Cheilymenia species (unidentified) | 1 | 2023 |
| fungus | Cheilymenia fimicola | a fungus | 3 | 2014 |
| fungus | Cheilymenia granulata | Cowpat Gem | 11 | 2014 |
| fungus | Cheilymenia stercorea | a fungus | 2 | 1999 |
| fungus | Chlorociboria aeruginascens | Green Elfcup | 49 | 2023 |
| fungus | Chlorociboria aeruginosa | Turquoise Elfcup | 1 | 2008 |
| fungus | Chlorophyllum brunneum | Brown Parasol | 6 | 2022 |
| fungus | Chlorophyllum olivieri | Conifer Parasol | 12 | 2013 |
| fungus | Chlorophyllum rhacodes | Shaggy Parasol | 86 | 2023 |
| fungus | Chondrostereum purpureum | Silverleaf Fungus | 59 | 2025 |
| fungus | Chromocyphella muscicola | Moss Ear | 2 | 2024 |
| fungus | Chroogomphus rutilus | Pine Spike-cap | 57 | 2022 |
| fungus | Chrysomphalina grossula | Green Navel | 2 | 2014 |
| fungus | Ciboria batschiana | an ascomycete fungus | 1 | 1970 |
| fungus | Cistella grevillei | an ascomycete fungus | 1 | 1999 |
| fungus | Clathrus archeri | Devil's Fingers | 4 | 2023 |
| fungus | Clavaria asperulospora | Prickly Spored Club | 2 | 2008 |
| fungus | Clavaria falcata | Pointed Club | 19 | 2014 |
| fungus | Clavaria fragilis | White Spindles | 24 | 2021 |
| fungus | Clavaria fumosa | Smoky Spindles | 16 | 2013 |
| fungus | Claviceps purpurea | an ergot fungus | 15 | 2021 |
| fungus | Claviceps purpurea var. purpurea | Ergot | 14 | 2017 |
| fungus | Claviceps spartinae | an ergot fungus | 6 | 2021 |
| fungus | Clavulina cinerea | Grey Coral | 53 | 2022 |
| fungus | Clavulina coralloides | Crested Coral | 46 | 2023 |
| fungus | Clavulina rugosa | Wrinkled Club | 37 | 2021 |
| fungus | Clavulinopsis corniculata | Meadow Coral | 64 | 2021 |
| fungus | Clavulinopsis fusiformis | Golden Spindles | 8 | 2022 |
| fungus | Clavulinopsis helvola | Yellow Club | 49 | 2022 |
| fungus | Clavulinopsis laeticolor | Handsome Club | 12 | 2022 |
| fungus | Clavulinopsis luteoalba | Apricot Club | 13 | 2022 |
| fungus | Clitocella popinalis | a basidiomycete fungus | 2 | 2006 |
| fungus | Clitocybe | a Clitocybe basidiomycete fungus (unidentified) | 8 | 2005 |
| fungus | Clitocybe agrestis | Field Funnel | 18 | 2013 |
| fungus | Clitocybe amarescens | a fungus | 5 | 2014 |
| fungus | Clitocybe americana | Wood Funnel | 1 | 2007 |
| fungus | Clitocybe angustissima | a basidiomycete fungus | 2 | 2006 |
| fungus | Clitocybe brumalis | Winter Funnel | 2 | 1985 |
| fungus | Clitocybe dealbata | Ivory Funnel | 10 | 2021 |
| fungus | Clitocybe diatreta | Pierced Funnel | 4 | 2012 |
| fungus | Clitocybe ditopus | Mealy Frosted Funnel | 11 | 2014 |
| fungus | Clitocybe ericetorum | a basidiomycete fungus | 2 | 1986 |
| fungus | Clitocybe fragrans | Fragrant Funnel | 140 | 2020 |
| fungus | Clitocybe harmajae | a basidiomycete fungus | 1 | 1996 |
| fungus | Clitocybe hydrogramma | a basidiomycete fungus | 19 | 2005 |
| fungus | Clitocybe infundibuliformis | Common Funnel Cap | 17 | 2009 |
| fungus | Clitocybe marginella | a fungus | 2 | 2010 |
| fungus | Clitocybe metachroa | Twotone Funnel | 88 | 2014 |
| fungus | Clitocybe nebularis | Clouded Agaric | 379 | 2024 |
| fungus | Clitocybe obsoleta | a basidiomycete fungus | 7 | 2003 |
| fungus | Clitocybe odora | Aniseed Toadstool | 27 | 2014 |
| fungus | Clitocybe phyllophila | Frosty Funnel | 54 | 2019 |
| fungus | Clitocybe rivulosa | Fool's Funnel | 161 | 2022 |
| fungus | Clitocybe subspadicea | Pale Date Funnel | 2 | 2003 |
| fungus | Clitocybe truncicola | Trunk Funnel | 1 | 2014 |
| fungus | Clitocybe umbilicata | a basidiomycete fungus | 1 | 1995 |
| fungus | Clitocybe vibecina | Mealy Funnel | 22 | 2020 |
| fungus | Clitopilus hobsonii | Miller's Oysterling | 5 | 2013 |
| fungus | Clitopilus prunulus | Miller (The) [fungus] | 193 | 2022 |
| fungus | Clonostachys ralfsii | an ascomycete fungus | 3 | 2014 |
| fungus | Cochliobolus verruculosus | a fungus | 1 | 2014 |
| fungus | Coleosporium tussilaginis s. lat. | a rust | 10 | 2023 |
| fungus | Coleroa robertiani | a fungus | 2 | 2017 |
| fungus | Collemataceae | a Collemataceae species (unidentified) | 1 | 2023 |
| fungus | Collybia cirrhata | Piggyback Shanklet | 3 | 2011 |
| fungus | Collybia cookei | Splitpea Shanklet | 6 | 2012 |
| fungus | Coniophora puteana | Cellar Fungus | 27 | 2015 |
| fungus | Conocybe | a Conocybe species (unidentified) | 3 | 2005 |
| fungus | Conocybe albipes non Fr., 1863 | Milky Conecap | 44 | 2023 |
| fungus | Conocybe alboradicans | Whiteroot Conecap | 1 | 1992 |
| fungus | Conocybe ambigua | Changeable Conecap | 8 | 2008 |
| fungus | Conocybe anthracophila | Bonfire Conecap | 1 | 2002 |
| fungus | Conocybe aurea | Golden Conecap | 1 | 2022 |
| fungus | Conocybe bisporigera | an agaric | 3 | 2010 |
| fungus | Conocybe brachypodii | Small Bulbed Conecap | 16 | 2014 |
| fungus | Conocybe dentatomarginata nom. nud. | Toothed Conecap | 14 | 2009 |
| fungus | Conocybe echinata | Grubby Conecap | 18 | 2009 |
| fungus | Conocybe enderlei | an agaric | 1 | 2006 |
| fungus | Conocybe farinacea | Mealy Conecap | 2 | 2010 |
| fungus | Conocybe fragilis | an agaric | 1 | 1999 |
| fungus | Conocybe fuscimarginata | Composting Conecap | 4 | 1991 |
| fungus | Conocybe hadrocystis | Stoutcyst Conecap | 2 | 2008 |
| fungus | Conocybe incarnata | Pinky Conecap | 1 | 1999 |
| fungus | Conocybe juniana | Stoppered Conecap | 2 | 2014 |
| fungus | Conocybe juniana var. juniana | an agaric | 19 | 2011 |
| fungus | Conocybe lenticulospora | Hairy Conecap | 3 | 2008 |
| fungus | Conocybe leucopus | Whitefooted Conecap | 4 | 1988 |
| fungus | Conocybe macrocephala | Bigheaded Conecap | 20 | 2013 |
| fungus | Conocybe macrospora | Bigspored Conecap | 10 | 2014 |
| fungus | Conocybe mesospora | Ginger Conecap | 34 | 2013 |
| fungus | Conocybe moseri | an agaric | 3 | 2005 |
| fungus | Conocybe pilosella | an agaric | 14 | 2010 |
| fungus | Conocybe plicatella | Fluted Conecap | 25 | 2010 |
| fungus | Conocybe pubescens | Callused Conecap | 15 | 2012 |
| fungus | Conocybe pulchella | Beautiful Conecap | 23 | 2011 |
| fungus | Conocybe pygmaeoaffinis | Hoary Conecap | 2 | 1992 |
| fungus | Conocybe rickeniana | Rusty Conecap | 13 | 2014 |
| fungus | Conocybe rickenii | Olive Conecap | 49 | 2014 |
| fungus | Conocybe rostellata | Stardew Conecap | 5 | 2013 |
| fungus | Conocybe semiglobata | Roundhead Conecap | 26 | 2014 |
| fungus | Conocybe siennophylla | Browngilled Conecap | 45 | 2012 |
| fungus | Conocybe siliginea | Pallid Conecap | 15 | 2014 |
| fungus | Conocybe subovalis | Ellipsoid Conecap | 15 | 2010 |
| fungus | Conocybe subpallida | a fungus | 6 | 2009 |
| fungus | Conocybe subpubescens | Downy Conecap | 5 | 2010 |
| fungus | Conocybe tenera | Brown Cone-cap | 11 | 2014 |
| fungus | Conocybe velutipes | Fleecyfoot Conecap | 15 | 2010 |
| fungus | Coprinellus | a Coprinellus species (unidentified) | 3 | 2023 |
| fungus | Coprinellus disseminatus | Fairy Inkcap | 96 | 2023 |
| fungus | Coprinellus domesticus | Firerug Inkcap | 46 | 2014 |
| fungus | Coprinellus ellisii | an agaric | 8 | 2009 |
| fungus | Coprinellus flocculosus | Flocculose Inkcap | 6 | 2008 |
| fungus | Coprinellus heptemerus | Dewdrop Inkcap | 1 | 1996 |
| fungus | Coprinellus micaceus | Glistening Ink-cap | 438 | 2024 |
| fungus | Coprinellus radians | an agaric | 2 | 2013 |
| fungus | Coprinellus silvaticus | Woodland Inkcap | 9 | 2000 |
| fungus | Coprinellus xanthothrix | Blond Inkcap | 16 | 2020 |
| fungus | Coprinopsis | a Coprinopsis species (unidentified) | 4 | 2023 |
| fungus | Coprinopsis acuminata | Humpback Inkcap | 2 | 2003 |
| fungus | Coprinopsis atramentaria | Common Ink-cap | 65 | 2022 |
| fungus | Coprinopsis candidata | White Inkcap | 1 | 2014 |
| fungus | Coprinopsis canoceps | an agaric | 2 | 2004 |
| fungus | Coprinopsis cinerea | Grey Inkcap | 4 | 2009 |
| fungus | Coprinopsis cortinata | Veiled Inkcap | 17 | 2012 |
| fungus | Coprinopsis cothurnata | Powdered Inkcap | 3 | 2014 |
| fungus | Coprinopsis echinospora | Warty Inkcap | 4 | 2000 |
| fungus | Coprinopsis friesii | Rhomboid Inkcap | 2 | 1989 |
| fungus | Coprinopsis herinkii | a fungus | 1 | 2002 |
| fungus | Coprinopsis jonesii | Bonfire Inkcap | 1 | 2008 |
| fungus | Coprinopsis lagopus | Hare'sfoot Inkcap | 5 | 2022 |
| fungus | Coprinopsis lagopus var. lagopus | Haresfoot Inkcap | 81 | 2018 |
| fungus | Coprinopsis lagopus var. vacillans | an agaric | 2 | 2009 |
| fungus | Coprinopsis marcescibilis | Ephemeral Inkcap | 12 | 2012 |
| fungus | Coprinopsis narcotica | Stinking Inkcap | 2 | 1985 |
| fungus | Coprinopsis nivea | Snowy Inkcap | 32 | 2013 |
| fungus | Coprinopsis pannucioides | Ragged Inkcap | 2 | 1990 |
| fungus | Coprinopsis phaeospora | Darkspored Inkcap | 2 | 2010 |
| fungus | Coprinopsis picacea | Magpie Fungus | 4 | 2018 |
| fungus | Coprinopsis pseudofriesii | Thorny Inkcap | 1 | 2013 |
| fungus | Coprinopsis pseudonivea | Aromatic Inkcap | 4 | 2009 |
| fungus | Coprinopsis radiata | Rayed Inkcap | 1 | 2009 |
| fungus | Coprinopsis spelaiophila | Cavity Inkcap | 9 | 2014 |
| fungus | Coprinopsis urticicola | Swamp Inkcap | 2 | 2010 |
| fungus | Coprinus | Inkcap | 6 | 2017 |
| fungus | Coprinus comatus | Shaggy Ink-cap | 93 | 2024 |
| fungus | Cordyceps militaris | Scarlet Caterpillar Fungus | 12 | 2022 |
| fungus | Coriolaceae | a Coriolaceae species (unidentified) | 1 | 2012 |
| fungus | Corticium | a Corticium species (unidentified) | 1 | 1970 |
| fungus | Cortinarius | a Cortinarius agaric (unidentified) | 13 | 2019 |
| fungus | Cortinarius acutus | Peaked Webcap | 2 | 2006 |
| fungus | Cortinarius alboviolaceus | Pearly Webcap | 4 | 2010 |
| fungus | Cortinarius ammophiloides | Ochreveiled Webcap | 5 | 2010 |
| fungus | Cortinarius amoenolens | Blueleg Webcap | 12 | 2004 |
| fungus | Cortinarius anomalus | Variable Webcap | 84 | 2014 |
| fungus | Cortinarius anthracinus | Smouldering Webcap | 1 | 2008 |
| fungus | Cortinarius armillatus | Red Banded Webcap | 1 | 2004 |
| fungus | Cortinarius balaustinus | Granulated Webcap | 5 | 2010 |
| fungus | Cortinarius bibulus | Swampling Webcap | 1 | 2005 |
| fungus | Cortinarius bivelus | Woollyfoot Webcap | 2 | 2010 |
| fungus | Cortinarius brunneofulvus | an agaric | 1 | 1987 |
| fungus | Cortinarius caerulescens | Mealy Bigfoot Webcap | 6 | 1998 |
| fungus | Cortinarius callochrous var. callochrous | an agaric | 10 | 2014 |
| fungus | Cortinarius callochrous var. parvus | an agaric | 2 | 2000 |
| fungus | Cortinarius caroviolaceus | Mealy Webcap | 1 | 1998 |
| fungus | Cortinarius casimirii | Umbonate Webcap | 3 | 2010 |
| fungus | Cortinarius cinnamomeus | Cinnamon Webcap | 5 | 2013 |
| fungus | Cortinarius cisticola | Rockrose Webcap | 4 | 2012 |
| fungus | Cortinarius croceocoeruleus | Handsome Webcap | 1 | 2014 |
| fungus | Cortinarius croceus | Saffron Webcap | 3 | 2013 |
| fungus | Cortinarius cyanopus | Bluefoot Webcap | 2 | 1990 |
| fungus | Cortinarius decipiens | an agaric | 10 | 2013 |
| fungus | Cortinarius decipiens var. decipiens | Sepia Webcap | 3 | 2008 |
| fungus | Cortinarius delibutus | Yellow Webcap | 1 | 1996 |
| fungus | Cortinarius dibaphus | Doubledyed Webcap | 1 | 1994 |
| fungus | Cortinarius elegantissimus | Dapper Webcap | 1 | 2008 |
| fungus | Cortinarius evernius | Silky Webcap | 3 | 1996 |
| fungus | Cortinarius flexipes | Pine Pelargonium Webcap | 3 | 2013 |
| fungus | Cortinarius glandicolor | Acorn Webcap | 1 | 1987 |
| fungus | Cortinarius glaucopus | Greenfoot Webcap | 6 | 2011 |
| fungus | Cortinarius helvelloides | Swamp Webcap | 6 | 2009 |
| fungus | Cortinarius hemitrichus | Frosty Webcap | 5 | 2012 |
| fungus | Cortinarius hinnuleus | Earthy Webcap | 3 | 2021 |
| fungus | Cortinarius imbutus | an agaric | 2 | 2010 |
| fungus | Cortinarius infractus | Bitter Webcap | 16 | 2010 |
| fungus | Cortinarius largus | Big Bellied Webcap | 2 | 2007 |
| fungus | Cortinarius livido-ochraceus | Wrinkled Webcap | 1 | 2005 |
| fungus | Cortinarius malachioides | Mallowlike Webcap | 2 | 1987 |
| fungus | Cortinarius obtusus | Blunt Webcap | 2 | 1990 |
| fungus | Cortinarius ochroleucus | Cream Webcap | 3 | 2005 |
| fungus | Cortinarius olearioides | Saffron Stainer | 5 | 2010 |
| fungus | Cortinarius olidus | Musty Webcap | 1 | 1998 |
| fungus | Cortinarius olivaceofuscus | Olivaceous Webcap | 4 | 2010 |
| fungus | Cortinarius osmophorus | Sweet Webcap | 1 | 1999 |
| fungus | Cortinarius paleaceus | an agaric | 5 | 1998 |
| fungus | Cortinarius privignoides | an agaric | 1 | 2009 |
| fungus | Cortinarius psammocephalus | Conical Webcap | 1 | 2005 |
| fungus | Cortinarius purpurascens | Bruising Webcap | 6 | 2014 |
| fungus | Cortinarius rigens | Rigid Webcap | 1 | 2005 |
| fungus | Cortinarius rigidus | an agaric | 2 | 2005 |
| fungus | Cortinarius roseipes | an agaric | 2 | 2011 |
| fungus | Cortinarius rufo-olivaceus | Mottled Webcap | 1 | 1999 |
| fungus | Cortinarius sanguineus | Bloodred Webcap | 3 | 2012 |
| fungus | Cortinarius saporatus | Stately Webcap | 1 | 1996 |
| fungus | Cortinarius saturninus | Trooping Webcap | 9 | 2010 |
| fungus | Cortinarius semisanguineus | Surprise Webcap | 1 | 2012 |
| fungus | Cortinarius simulatus | Copycat Webcap | 1 | 2007 |
| fungus | Cortinarius sodagnitus | Bitter Bigfoot Webcap | 2 | 2007 |
| fungus | Cortinarius stillatitius | Purple Stocking Webcap | 1 | 2000 |
| fungus | Cortinarius subbalaustinus | Burnt Orange Webcap | 6 | 2010 |
| fungus | Cortinarius tabularis | Wan Webcap | 1 | 1970 |
| fungus | Cortinarius torvus | Stocking Webcap | 1 | 2000 |
| fungus | Cortinarius triumphans | Birch Webcap | 2 | 1994 |
| fungus | Cortinarius trivialis | Girdled Webcap | 1 | 1999 |
| fungus | Cortinarius umbrinolens | Umber Webcap | 12 | 2013 |
| fungus | Cortinarius variicolor | Contrary Webcap | 2 | 1996 |
| fungus | Cortinarius venetus | Fluorescent Webcap | 1 | 2005 |
| fungus | Cortinarius violaceus | Violet Webcap | 1 | 2021 |
| fungus | Craterellus cornucopioides | Horn of Plenty | 4 | 2021 |
| fungus | Craterellus sinuosus | Sinuous Chanterelle | 14 | 2001 |
| fungus | Crepidotus applanatus | an agaric | 9 | 2023 |
| fungus | Crepidotus applanatus var. applanatus | Flat Oysterling | 11 | 2013 |
| fungus | Crepidotus autochthonus | Grounded Oysterling | 6 | 2008 |
| fungus | Crepidotus calolepis | Scaly Oysterling | 2 | 2023 |
| fungus | Crepidotus caspari | Pale Oysterling | 18 | 2021 |
| fungus | Crepidotus cesatii | Roundspored Oysterling | 82 | 2022 |
| fungus | Crepidotus cesatii var. subsphaerosporus | an agaric | 22 | 2002 |
| fungus | Crepidotus epibryus | Grass Oysterling | 16 | 2020 |
| fungus | Crepidotus luteolus | Yellowing Oysterling | 11 | 2020 |
| fungus | Crepidotus mollis | Soft Slipper Toadstool | 80 | 2023 |
| fungus | Crepidotus variabilis | Variable Oysterling | 71 | 2022 |
| fungus | Crepidotus versutus | Downy Oysterling | 4 | 2009 |
| fungus | Crinipellis scabella | Hairy Parachute | 27 | 2022 |
| fungus | Cristulariella depraedans | Sycamore Leafspot | 9 | 2014 |
| fungus | Crucibulum laeve | White-egg Bird's Nest | 6 | 2019 |
| fungus | Cryptosphaeria eunomia | an ascomycete fungus | 1 | 2010 |
| fungus | Cryptostroma corticale | a fungus | 1 | 1987 |
| fungus | Cryptovalsa protracta | an ascomycete fungus | 2 | 1999 |
| fungus | Cudoniella acicularis | Oak Pin | 2 | 2008 |
| fungus | Cuphophyllus colemannianus | Toasted Waxcap | 17 | 2013 |
| fungus | Cuphophyllus flavipes | Yellowfoot Waxcap | 20 | 2010 |
| fungus | Cuphophyllus fornicatus | Earthy Waxcap | 11 | 2021 |
| fungus | Cuphophyllus pratensis var. pallidus | Pale Waxcap | 2 | 2013 |
| fungus | Cuphophyllus pratensis var. pratensis | Meadow Wax-cap | 134 | 2024 |
| fungus | Cuphophyllus russocoriaceus | Cedarwood Waxcap | 51 | 2019 |
| fungus | Cuphophyllus virgineus var. fuscescens | a basidiomycete fungus | 2 | 2003 |
| fungus | Cuphophyllus virgineus var. ochraceopallidus | a basidiomycete fungus | 12 | 2014 |
| fungus | Cuphophyllus virgineus var. virgineus | Snowy Wax-cap | 289 | 2023 |
| fungus | Cyanoboletus pulverulentus | Inkstain Bolete | 4 | 2010 |
| fungus | Cyathicula cyathoidea | an ascomycete fungus | 6 | 1999 |
| fungus | Cyathus olla | Field Bird's Nest | 10 | 2019 |
| fungus | Cyathus stercoreus | Dung Bird's Nest | 4 | 2022 |
| fungus | Cyathus striatus | Fluted Bird's Nest | 23 | 2022 |
| fungus | Cyclocybe cylindracea | Poplar Fieldcap | 36 | 2014 |
| fungus | Cyclocybe erebia | Dark Fieldcap | 15 | 2013 |
| fungus | Cylindrobasidium | a Cylindrobasidium species (unidentified) | 1 | 2012 |
| fungus | Cylindrobasidium laeve | Tear Dropper | 13 | 2013 |
| fungus | Cymadothea trifolii | a fungus | 2 | 2010 |
| fungus | Cystoderma amianthinum | Earthy Powdercap | 76 | 2022 |
| fungus | Cystoderma simulatum | Woody Powdercap | 1 | 2015 |
| fungus | Cystodermella granulosa | Granular Powdercap | 1 | 2005 |
| fungus | Cystolepiota adulterina | Suspected Dapperling | 10 | 2003 |
| fungus | Cystolepiota bucknallii | Lilac Dapperling | 17 | 2007 |
| fungus | Cystolepiota fumosifolia | Yellowcelled Dapperling | 1 | 2013 |
| fungus | Cystolepiota hetieri | Flushing Dapperling | 13 | 2008 |
| fungus | Cystolepiota moelleri | Rosy Dapperling | 4 | 2008 |
| fungus | Cystolepiota seminuda | Bearded Dapperling | 53 | 2021 |
| fungus | Cystolepiota sistrata | an agaric | 29 | 2001 |
| grasshopper, cricket or true cricket | Chorthippus | a Chorthippus species (unidentified) | 6 | 2008 |
| grasshopper, cricket or true cricket | Chorthippus albomarginatus | Lesser Marsh Grasshopper | 78 | 2024 |
| grasshopper, cricket or true cricket | Chorthippus brunneus | Common Field Grasshopper | 950 | 2025 |
| grasshopper, cricket or true cricket | Conocephalus | a Conocephalus species (unidentified) | 10 | 2018 |
| grasshopper, cricket or true cricket | Conocephalus dorsalis | Short-winged Conehead | 205 | 2025 |
| grasshopper, cricket or true cricket | Conocephalus fuscus | Long-winged Conehead | 337 | 2024 |
| lichen | Calicium glaucellum | a lichen | 2 | 1996 |
| lichen | Callome multipartita | a lichen | 2 | 2005 |
| lichen | Calogaya decipiens | a lichen | 6 | 2022 |
| lichen | Calogaya pusilla | a lichen | 12 | 2011 |
| lichen | Caloplaca | a Caloplaca species (unidentified) | 1 | 2009 |
| lichen | Caloplaca aurea | a lichen | 1 | 2014 |
| lichen | Caloplaca cerina | a lichen | 1 | 2011 |
| lichen | Caloplaca chlorina | a lichen | 1 | 2020 |
| lichen | Candelaria concolor | a lichen | 6 | 2023 |
| lichen | Candelariella aurella | a lichen | 1 | 2009 |
| lichen | Candelariella aurella f. aurella | a lichen | 20 | 2014 |
| lichen | Candelariella medians f. medians | a lichen | 8 | 2020 |
| lichen | Candelariella reflexa | a lichen | 9 | 2020 |
| lichen | Candelariella vitellina | a lichen | 7 | 2020 |
| lichen | Candelariella vitellina f. flavovirella | a lichen | 1 | 1996 |
| lichen | Candelariella vitellina f. vitellina | a lichen | 37 | 2018 |
| lichen | Candelariella xanthostigma | a lichen | 1 | 2011 |
| lichen | Catillaria atomarioides | a lichen | 2 | 2014 |
| lichen | Catillaria chalybeia | a lichen | 1 | 2014 |
| lichen | Catillaria chalybeia var. chalybeia | a lichen | 12 | 2014 |
| lichen | Catillaria lenticularis | a lichen | 27 | 2018 |
| lichen | Catillaria nigroclavata | a lichen | 4 | 2016 |
| lichen | Chaenotheca brunneola | Pinhead Lichen | 1 | 1988 |
| lichen | Chaenotheca chrysocephala | a lichen | 1 | 1988 |
| lichen | Chaenotheca ferruginea | a lichen | 6 | 2011 |
| lichen | Chaenotheca hispidula | a lichen | 1 | 1988 |
| lichen | Chrysothrix candelaris | a lichen | 3 | 1996 |
| lichen | Chrysothrix flavovirens | a lichen | 1 | 1988 |
| lichen | Circinaria caesiocinerea | a lichen | 7 | 2011 |
| lichen | Circinaria calcarea | a lichen | 46 | 2020 |
| lichen | Circinaria contorta | a lichen | 26 | 2018 |
| lichen | Circinaria hoffmanniana | a lichen | 4 | 2018 |
| lichen | Cladonia | Cup Lichen | 13 | 2023 |
| lichen | Cladonia cervicornis | a lichen | 2 | 2009 |
| lichen | Cladonia chlorophaea s. lat. | a lichen | 7 | 2020 |
| lichen | Cladonia coniocraea | a lichen | 15 | 2020 |
| lichen | Cladonia convoluta | a lichen | 5 | 2016 |
| lichen | Cladonia crispata var. crispata | a lichen | 2 | 1998 |
| lichen | Cladonia fimbriata | a lichen | 20 | 2023 |
| lichen | Cladonia floerkeana | Gritty British Soldiers | 1 | 2023 |
| lichen | Cladonia foliacea | a lichen | 2 | 2016 |
| lichen | Cladonia furcata | a lichen | 3 | 2020 |
| lichen | Cladonia furcata subsp. furcata | a lichen | 4 | 2016 |
| lichen | Cladonia furcata subsp. subrangiformis | a lichen | 4 | 2018 |
| lichen | Cladonia macilenta | a lichen | 1 | 1993 |
| lichen | Cladonia pocillum | a lichen | 8 | 2020 |
| lichen | Cladonia polydactyla | a lichen | 2 | 2010 |
| lichen | Cladonia portentosa | Reindeer Moss | 12 | 2023 |
| lichen | Cladonia pyxidata | a lichen | 10 | 2018 |
| lichen | Cladonia ramulosa | a lichen | 1 | 2009 |
| lichen | Cladonia rangiformis | a lichen | 19 | 2020 |
| lichen | Cladonia squamosa s. lat. | a lichen | 2 | 2016 |
| lichen | Cladonia subcervicornis | a lichen | 3 | 2009 |
| lichen | Cladonia symphycarpa | a lichen | 1 | 1991 |
| lichen | Clathroporinopsis nidarosiensis | a lichen | 3 | 2018 |
| lichen | Clauzadea chondrodes | a lichen | 2 | 2018 |
| lichen | Clauzadea immersa | a lichen | 9 | 2018 |
| lichen | Clauzadea metzleri | a lichen | 4 | 2018 |
| lichen | Clauzadea monticola | a lichen | 12 | 2021 |
| lichen | Cliostomum griffithii | a lichen | 5 | 2020 |
| lichen | Coenogonium pineti | a lichen | 2 | 1991 |
| lichen | Collema | a Collema species (unidentified) | 1 | 2019 |
| lichen | Coniocarpon cinnabarinum | a lichen | 2 | 1998 |
| lichen | Cresponea premnea | a lichen | 4 | 1996 |
| liverwort | Calypogeia arguta | Notched Pouchwort | 8 | 2023 |
| liverwort | Calypogeia fissa | Common Pouchwort | 17 | 2022 |
| liverwort | Calypogeia muelleriana | Mueller's Pouchwort | 2 | 1994 |
| liverwort | Cephalozia | A Cephalozia liverwort (unidentified) | 1 | 1903 |
| liverwort | Cephalozia bicuspidata | Two-horned Pincerwort | 6 | 2023 |
| liverwort | Cephalozia curvifolia | Wood-rust | 8 | 2019 |
| liverwort | Cephaloziella | A Cephaloziella liverwort (unidentified) | 1 | 2004 |
| liverwort | Cephaloziella divaricata | Common Threadwort | 2 | 2021 |
| liverwort | Cephaloziella hampeana | Hampe's Threadwort | 1 | 2007 |
| liverwort | Cephaloziella rubella | Red Threadwort | 1 | 1990 |
| liverwort | Chiloscyphus pallescens | St Winifrid's Other Moss | 3 | 2019 |
| liverwort | Chiloscyphus polyanthos | St Winifrid's Moss | 3 | 2021 |
| liverwort | Conocephalum conicum s.str. | Great Scented Liverwort | 54 | 2023 |
| mammal | Capra hircus | Feral Goat | 2 | 2019 |
| mammal | Capreolus capreolus | Roe Deer | 2758 | 2025 |
| mammal | Castor fiber | Beaver | 2 | 2023 |
| mammal | Cervidae | deer | 141 | 2025 |
| mammal | Cervus elaphus | Red Deer | 18 | 2019 |
| mammal | Cervus nippon | Sika Deer | 3 | 1998 |
| mammal | Cricetidae | a vole (unidentified) | 106 | 2025 |
| mammal | Cricetidae or Muridae | a vole or mouse (unidentified) | 7 | 2015 |
| mammal | Cricetidae or Muridae or Myoxidae | a vole or mouse or dormouse (unidentified) | 3 | 2022 |
| mammal - bat | Chiroptera | Bat | 988 | 2025 |
| mammal - marine | Cetacea | Whales & Dolphins | 1 | 1620 |
| mayfly | Caenis | a Caenis mayfly (unidentified) | 1 | 2004 |
| mayfly | Caenis horaria | a mayfly | 6 | 2012 |
| mayfly | Caenis luctuosa | Angler's Curse | 8 | 2004 |
| mayfly | Caenis macrura | a mayfly | 1 | 2010 |
| mayfly | Caenis rivulorum | a mayfly | 1 | 2021 |
| mayfly | Caenis robusta | a mayfly | 19 | 2013 |
| mayfly | Centroptilum luteolum | a mayfly | 3 | 2024 |
| mayfly | Cloeon | a Cloeon species (unidentified) | 1 | 2021 |
| mayfly | Cloeon dipterum | Pond Olive | 162 | 2024 |
| mayfly | Cloeon simile | a mayfly | 8 | 2013 |
| millipede | Chordeuma proximum/sylvestre | a Chordeuma millipede (unidentified) | 1 | 1998 |
| millipede | Cylindroiulus | a Cylindroiulus species (unidentified) | 5 | 2023 |
| millipede | Cylindroiulus caeruleocinctus | a julid snake millipede | 8 | 2023 |
| millipede | Cylindroiulus latestriatus | a julid snake millipede | 1 | 1995 |
| millipede | Cylindroiulus punctatus | Blunt-tailed Snake Millipede | 25 | 2023 |
| mollusc | Carychium | a herald snail | 3 | 2006 |
| mollusc | Carychium minimum | Short-toothed Herald Snail | 5 | 2004 |
| mollusc | Carychium tridentatum | Long-toothed Herald Snail | 19 | 2006 |
| mollusc | Cecilioides (Cecilioides) acicula | Blind Snail | 4 | 2000 |
| mollusc | Cepaea | a Cepaea species (unidentified) | 37 | 2023 |
| mollusc | Cepaea (Cepaea) agg. | a cepaea snail | 3 | 2017 |
| mollusc | Cepaea (Cepaea) hortensis | White-lipped Snail | 400 | 2023 |
| mollusc | Cepaea (Cepaea) nemoralis | Brown Lipped Snail | 386 | 2025 |
| mollusc | Cepaea/Helix sp. | a Cepaea or Helix snail (unidentified) | 16 | 2009 |
| mollusc | Cerastoderma edule | Common Cockle | 4 | 2019 |
| mollusc | Cerastoderma glaucum | Lagoon Cockle | 3 | 1972 |
| mollusc | Cernuella (Cernuella) virgata | Banded Snail | 55 | 2022 |
| mollusc | Clausilia | a Clausilia species (unidentified) | 1 | 2023 |
| mollusc | Clausilia (Clausilia) bidentata | Two-toothed Door Snail | 103 | 2023 |
| mollusc | Clausiliidae | a Clausiliidae species (unidentified) | 1 | 2023 |
| mollusc | Cochlicella (Cochlicella) acuta | Pointed Snail | 12 | 2022 |
| mollusc | Cochlicella (Prietocella) barbara | a snail | 1 | 2019 |
| mollusc | Cochlicopa | a Cochlicopa species (unidentified) | 5 | 2023 |
| mollusc | Cochlicopa cf. lubrica or Cochlicopa cf. lubricella (unidentified) | Slippery Moss Snail or Least Slippery Snail (unidentified) | 1 | 2007 |
| mollusc | Cochlicopa cf. lubrica sensu Anderson 2008 | Slippery Moss Snail | 85 | 2018 |
| mollusc | Cochlicopa cf. lubricella sensu Anderson 2008 | Least Slippery Snail | 18 | 2014 |
| mollusc | Cochlicopa lubrica agg. | a mollusc | 4 | 2016 |
| mollusc | Cochlodina (Cochlodina) laminata | Plaited Door Snail | 69 | 2023 |
| mollusc | Columella aspera | a chrysalis snail | 1 | 1983 |
| mollusc | Columella edentula | Toothless Chrysalis Snail | 3 | 2020 |
| mollusc | Columella edentula agg. | a chrysalis snail | 2 | 2004 |
| mollusc | Cornu aspersum | Common Garden Snail | 1004 | 2024 |
| mollusc | Crepidula fornicata | American Slipper Limpet | 2 | 2019 |
| moss | Calliergon | a Calliergon species (unidentified) | 1 | 2013 |
| moss | Calliergonella | a Calliergonella species (unidentified) | 2 | 2009 |
| moss | Calliergonella cuspidata | Pointed Spear-moss | 213 | 2023 |
| moss | Campylium chrysophyllum | Golden Feather-moss | 1 | 2017 |
| moss | Campylium protensum | a moss | 1 | 1963 |
| moss | Campylium stellatum s.str. | Yellow Starry Feather-moss | 4 | 2020 |
| moss | Campylophyllopsis calcarea | Chalk Feather-moss | 1 | 2023 |
| moss | Campylopus flexuosus | Rusty Swan-neck Moss | 3 | 2023 |
| moss | Campylopus introflexus | Heath Star Moss | 29 | 2022 |
| moss | Campylopus pyriformis | Dwarf Swan-neck Moss | 3 | 2023 |
| moss | Campylopus shawii | Shaw's Swan-neck Moss | 2 | 1978 |
| moss | Ceratodon conicus | Scarce Redshank | 2 | 2019 |
| moss | Ceratodon purpureus | Redshank (moss) | 138 | 2023 |
| moss | Cheilothela chloropus | Rabbit Moss | 3 | 2015 |
| moss | Cirriphyllum crassinervium | Beech Feather-moss | 18 | 2023 |
| moss | Cirriphyllum piliferum | Hair-pointed Feather-moss | 37 | 2023 |
| moss | Climacium dendroides | Tree-moss | 3 | 2023 |
| moss | Cratoneuron filicinum | Fern-leaved Hook-moss | 39 | 2023 |
| moss | Cryphaea heteromalla | Lateral Cryphaea | 143 | 2023 |
| moss | Ctenidium | a Ctenidium species (unidentified) | 1 | 2019 |
| moss | Ctenidium molluscum | Chalk Comb-moss | 69 | 2023 |
| moss | Cynodontium bruntonii | Brunton's Dog-tooth | 1 | 1990 |
| moth or butterfly - butterfly | Callophrys rubi | Green Hairstreak | 660 | 2023 |
| moth or butterfly - butterfly | Celastrina argiolus | Holly Blue | 12989 | 2025 |
| moth or butterfly - butterfly | Celastrina argiolus britanna | Holly Blue | 11 | 2023 |
| moth or butterfly - butterfly | Coenonympha pamphilus | Small Heath | 3798 | 2025 |
| moth or butterfly - butterfly | Colias croceus | Clouded Yellow | 1149 | 2023 |
| moth or butterfly - butterfly | Colias croceus form helice | Clouded Yellow (pale f.) | 4 | 2000 |
| moth or butterfly - butterfly | Colias hyale | Pale Clouded Yellow | 11 | 2000 |
| moth or butterfly - butterfly | Cupido minimus | Small Blue | 467 | 2023 |
| moth or butterfly - macro moth | Cabera | a Cabera species (unidentified) | 1 | 2016 |
| moth or butterfly - macro moth | Cabera exanthemata | Common Wave | 661 | 2025 |
| moth or butterfly - macro moth | Cabera pusaria | Common White Wave | 695 | 2024 |
| moth or butterfly - macro moth | Callimorpha dominula | Scarlet Tiger | 1435 | 2025 |
| moth or butterfly - macro moth | Callistege mi | Mother Shipton | 177 | 2023 |
| moth or butterfly - macro moth | Calliteara pudibunda | Pale Tussock | 1209 | 2024 |
| moth or butterfly - macro moth | Calophasia lunula | Toadflax Brocade | 13 | 2024 |
| moth or butterfly - macro moth | Campaea margaritaria | Light Emerald | 1778 | 2024 |
| moth or butterfly - macro moth | Camptogramma bilineata | Yellow Shell | 1783 | 2025 |
| moth or butterfly - macro moth | Camptogramma bilineata subsp. bilineata | a Yellow Shell | 17 | 2011 |
| moth or butterfly - macro moth | Caradrina clavipalpis | Pale Mottled Willow | 2554 | 2024 |
| moth or butterfly - macro moth | Caradrina kadenii | Clancy's Rustic | 2 | 2022 |
| moth or butterfly - macro moth | Caradrina morpheus | Mottled Rustic | 1364 | 2024 |
| moth or butterfly - macro moth | Catarhoe cuculata | Royal Mantle | 10 | 2018 |
| moth or butterfly - macro moth | Catarhoe rubidata | Ruddy Carpet | 33 | 2020 |
| moth or butterfly - macro moth | Catocala fraxini | Clifden Nonpareil | 53 | 2023 |
| moth or butterfly - macro moth | Catocala nupta | Red Underwing | 358 | 2024 |
| moth or butterfly - macro moth | Catocala promissa | Light Crimson Underwing | 1 | 2020 |
| moth or butterfly - macro moth | Catocala sponsa | Dark Crimson Underwing | 3 | 2022 |
| moth or butterfly - macro moth | Cepphis advenaria | Little Thorn | 68 | 2025 |
| moth or butterfly - macro moth | Ceramica pisi | Broom Moth | 37 | 2021 |
| moth or butterfly - macro moth | Cerapteryx graminis | Antler | 34 | 2023 |
| moth or butterfly - macro moth | Cerastis rubricosa | Red Chestnut | 80 | 2024 |
| moth or butterfly - macro moth | Cerura vinula | Puss Moth | 194 | 2024 |
| moth or butterfly - macro moth | Charanyca trigrammica | Treble Lines | 1949 | 2024 |
| moth or butterfly - macro moth | Charissa obscurata | Annulet | 25 | 2023 |
| moth or butterfly - macro moth | Chesias legatella | Streak | 3 | 1996 |
| moth or butterfly - macro moth | Chesias rufata | Broom-tip | 1 | 1952 |
| moth or butterfly - macro moth | Chiasmia clathrata | Latticed Heath | 447 | 2024 |
| moth or butterfly - macro moth | Chilodes maritima | Silky Wainscot | 51 | 2023 |
| moth or butterfly - macro moth | Chloroclysta miata | Autumn Green Carpet | 31 | 2022 |
| moth or butterfly - macro moth | Chloroclysta siterata | Red-green Carpet | 566 | 2024 |
| moth or butterfly - macro moth | Chloroclystis v-ata | V-Pug | 1122 | 2025 |
| moth or butterfly - macro moth | Chrysodeixis chalcites | Golden Twin-spot | 1 | 1979 |
| moth or butterfly - macro moth | Cidaria fulvata | Barred Yellow | 394 | 2024 |
| moth or butterfly - macro moth | Cilix glaucata | Chinese Character | 802 | 2024 |
| moth or butterfly - macro moth | Cirrhia gilvago | Dusky-lemon Sallow | 21 | 2018 |
| moth or butterfly - macro moth | Cirrhia icteritia | Sallow (moth) | 237 | 2024 |
| moth or butterfly - macro moth | Cirrhia ocellaris | Pale-lemon Sallow | 2 | 2011 |
| moth or butterfly - macro moth | Cleorodes lichenaria | Brussels Lace | 182 | 2024 |
| moth or butterfly - macro moth | Clostera curtula | Chocolate-tip | 262 | 2024 |
| moth or butterfly - macro moth | Coenobia rufa | Small Rufous | 23 | 2024 |
| moth or butterfly - macro moth | Colocasia coryli | Nut-tree Tussock | 947 | 2024 |
| moth or butterfly - macro moth | Colostygia multistrigaria | Mottled Grey | 27 | 2023 |
| moth or butterfly - macro moth | Colostygia olivata | Beech-green Carpet | 12 | 2004 |
| moth or butterfly - macro moth | Colostygia pectinataria | Green Carpet | 1679 | 2025 |
| moth or butterfly - macro moth | Colotois pennaria | Feathered Thorn | 570 | 2024 |
| moth or butterfly - macro moth | Comibaena bajularia | Blotched Emerald | 27 | 2024 |
| moth or butterfly - macro moth | Conistra | a Conistra species (unidentified) | 1 | 2021 |
| moth or butterfly - macro moth | Conistra ligula | Dark Chestnut | 175 | 2024 |
| moth or butterfly - macro moth | Conistra rubiginea | Dotted Chestnut | 128 | 2024 |
| moth or butterfly - macro moth | Conistra vaccinii | Chestnut (moth) | 475 | 2024 |
| moth or butterfly - macro moth | Cosmia affinis | Lesser-spotted Pinion | 49 | 2023 |
| moth or butterfly - macro moth | Cosmia diffinis | White-spotted Pinion | 10 | 2022 |
| moth or butterfly - macro moth | Cosmia pyralina | Lunar-spotted Pinion | 117 | 2023 |
| moth or butterfly - macro moth | Cosmia trapezina | Dun-bar | 1050 | 2025 |
| moth or butterfly - macro moth | Cosmorhoe ocellata | Purple Bar | 368 | 2024 |
| moth or butterfly - macro moth | Cossus cossus | Goat Moth | 9 | 1971 |
| moth or butterfly - macro moth | Craniophora ligustri | Coronet | 1681 | 2025 |
| moth or butterfly - macro moth | Crocallis elinguaria | Scalloped Oak | 2451 | 2025 |
| moth or butterfly - macro moth | Cryphia algae | Tree-lichen Beauty | 1 | 2022 |
| moth or butterfly - macro moth | Cryphia muralis form impar | Marbled Green f.impar (E & W England) | 12 | 2011 |
| moth or butterfly - macro moth | Cucullia absinthii | Wormwood (moth) | 6 | 2018 |
| moth or butterfly - macro moth | Cucullia chamomillae | Chamomile Shark | 17 | 2020 |
| moth or butterfly - macro moth | Cucullia lychnitis | Striped Lychnis | 1 | 1952 |
| moth or butterfly - macro moth | Cucullia umbratica | Shark | 246 | 2024 |
| moth or butterfly - macro moth | Cucullia verbasci | Mullein Moth | 384 | 2024 |
| moth or butterfly - macro moth | Cybosia mesomella | Four-dotted Footman | 8 | 2022 |
| moth or butterfly - macro moth | Cyclophora albipunctata | Birch Mocha | 6 | 2008 |
| moth or butterfly - macro moth | Cyclophora annularia | Mocha | 383 | 2025 |
| moth or butterfly - macro moth | Cyclophora linearia | Clay Triple-lines | 187 | 2024 |
| moth or butterfly - macro moth | Cyclophora pendularia | Dingy Mocha | 2 | 1965 |
| moth or butterfly - macro moth | Cyclophora porata | False Mocha | 2 | 1940 |
| moth or butterfly - macro moth | Cyclophora punctaria | Maiden's Blush | 377 | 2025 |
| moth or butterfly - macro moth | Cyclophora puppillaria | Blair's Mocha | 5 | 2022 |
| moth or butterfly - macro moth | Cymatophorina diluta | Oak Lutestring | 9 | 1991 |
| moth or butterfly - micro moth | Cacoecimorpha pronubana | Carnation Tortrix | 121 | 2023 |
| moth or butterfly - micro moth | Calamotropha paludella | Bulrush Veneer | 124 | 2024 |
| moth or butterfly - micro moth | Callisto denticulella | Apple Nymph | 17 | 2022 |
| moth or butterfly - micro moth | Caloptilia | a Caloptilia micro-moth (unidentified) | 11 | 2023 |
| moth or butterfly - micro moth | Caloptilia alchimiella | Yellow-triangle Slender | 23 | 2022 |
| moth or butterfly - micro moth | Caloptilia azaleella | Azalea Leaf Miner | 8 | 2022 |
| moth or butterfly - micro moth | Caloptilia betulicola | Red Birch Slender | 11 | 2022 |
| moth or butterfly - micro moth | Caloptilia cuculipennella | Privet Stilt | 8 | 2021 |
| moth or butterfly - micro moth | Caloptilia elongella | Alder Stilt | 38 | 2022 |
| moth or butterfly - micro moth | Caloptilia falconipennella | Dark Alder Stilt | 6 | 2022 |
| moth or butterfly - micro moth | Caloptilia hauderi | Yellow-blotch Slender | 2 | 2011 |
| moth or butterfly - micro moth | Caloptilia hemidactylella | Scarce Maple Stilt | 4 | 2023 |
| moth or butterfly - micro moth | Caloptilia honoratella | Pale Maple Stilt | 1 | 2023 |
| moth or butterfly - micro moth | Caloptilia populetorum | Black-dot Stilt | 14 | 2023 |
| moth or butterfly - micro moth | Caloptilia robustella | Shaded Oak Stilt | 33 | 2022 |
| moth or butterfly - micro moth | Caloptilia rufipennella | Rufous Stilt | 83 | 2023 |
| moth or butterfly - micro moth | Caloptilia semifascia | Maple Stilt | 234 | 2024 |
| moth or butterfly - micro moth | Caloptilia stigmatella | Willow Stilt | 82 | 2023 |
| moth or butterfly - micro moth | Calybites phasianipennella | White-marked Stilt | 1 | 2018 |
| moth or butterfly - micro moth | Cameraria ohridella | Horse-Chestnut Leaf-miner | 500 | 2024 |
| moth or butterfly - micro moth | Capperia britanniodactylus | Wood Sage Plume | 14 | 2024 |
| moth or butterfly - micro moth | Capua vulgana | Common Twist | 36 | 2024 |
| moth or butterfly - micro moth | Carcina quercana | Long-horned Flat-body | 766 | 2025 |
| moth or butterfly - micro moth | Carpatolechia alburnella | Birch Grey | 4 | 2015 |
| moth or butterfly - micro moth | Carpatolechia decorella | Black-shouldered Grey | 3 | 2020 |
| moth or butterfly - micro moth | Carpatolechia fugitivella | Elm Grey | 5 | 2023 |
| moth or butterfly - micro moth | Carpatolechia proximella | Spotted Birch Grey | 5 | 2023 |
| moth or butterfly - micro moth | Caryocolum | a Caryocolum species (unidentified) | 2 | 2021 |
| moth or butterfly - micro moth | Caryocolum blandella | Short-barred Groundling | 2 | 1994 |
| moth or butterfly - micro moth | Caryocolum blandulella | Southern Barred Groundling | 1 | 1994 |
| moth or butterfly - micro moth | Caryocolum viscariella | Campion Groundling | 3 | 2020 |
| moth or butterfly - micro moth | Cataclysta lemnata | Small China-mark | 495 | 2025 |
| moth or butterfly - micro moth | Cataclysta sp. or Elophila sp. (unditentified) | a china-mark moth (unidentified) | 3 | 2011 |
| moth or butterfly - micro moth | Catoptria falsella | Chequered Grass-moth | 52 | 2023 |
| moth or butterfly - micro moth | Catoptria margaritella | Silver-stripe Grass-veneer | 3 | 2022 |
| moth or butterfly - micro moth | Catoptria pinella | Pearl Grass-moth | 85 | 2024 |
| moth or butterfly - micro moth | Cauchas fibulella | Speedwell Longhorn | 42 | 2022 |
| moth or butterfly - micro moth | Cauchas rufimitrella | Meadow Longhorn | 81 | 2024 |
| moth or butterfly - micro moth | Cedestis gysseleniella | Double-barred Needle-miner | 2 | 2019 |
| moth or butterfly - micro moth | Cedestis subfasciella | Barred Needle-miner | 8 | 2021 |
| moth or butterfly - micro moth | Celypha aurofasciana | Gold-barred Marble | 5 | 2024 |
| moth or butterfly - micro moth | Celypha cespitana | Thyme Marble | 14 | 2024 |
| moth or butterfly - micro moth | Celypha lacunana | Common Marble | 2188 | 2025 |
| moth or butterfly - micro moth | Celypha rivulana | Silver-striped Marble | 2 | 2005 |
| moth or butterfly - micro moth | Celypha striana | Barred Marble | 1737 | 2024 |
| moth or butterfly - micro moth | Celypha woodiana | Mistletoe Marble | 8 | 2022 |
| moth or butterfly - micro moth | Chilo phragmitella | Reed Veneer | 21 | 2022 |
| moth or butterfly - micro moth | Chionodes fumatella | Smoky Groundling | 1 | 2001 |
| moth or butterfly - micro moth | Choreutis pariana | Apple Leaf Skeletoniser | 22 | 2021 |
| moth or butterfly - micro moth | Choristoneura diversana | Wood Tortrix | 2 | 2014 |
| moth or butterfly - micro moth | Choristoneura hebenstreitella | Great Tortrix | 1 | 1994 |
| moth or butterfly - micro moth | Chrysoclista linneella | Lime Flame | 10 | 2023 |
| moth or butterfly - micro moth | Chrysoesthia drurella | Fiery Miner | 1 | 2013 |
| moth or butterfly - micro moth | Chrysoesthia sexguttella | Orange-spotted Miner | 8 | 2023 |
| moth or butterfly - micro moth | Chrysoteuchia culmella | Garden Grass-veneer | 3839 | 2025 |
| moth or butterfly - micro moth | Clavigesta purdeyi | Pine Leaf-mining Moth | 16 | 2023 |
| moth or butterfly - micro moth | Clepsis consimilana | Privet Twist | 562 | 2024 |
| moth or butterfly - micro moth | Clepsis spectrana | Cyclamen Tortrix | 186 | 2022 |
| moth or butterfly - micro moth | Cnephasia | a tortrix moth (unidentified) | 209 | 2024 |
| moth or butterfly - micro moth | Cnephasia asseclana | Flax Tortrix | 158 | 2024 |
| moth or butterfly - micro moth | Cnephasia communana | Southern Grey Tortrix | 36 | 2023 |
| moth or butterfly - micro moth | Cnephasia conspersana | Coast Grey Tortrix | 6 | 2022 |
| moth or butterfly - micro moth | Cnephasia incertana | Light Grey Tortrix | 157 | 2023 |
| moth or butterfly - micro moth | Cnephasia longana | Buff Grey Tortrix | 7 | 2019 |
| moth or butterfly - micro moth | Cnephasia pasiuana | Meadow Grey Tortrix | 3 | 2005 |
| moth or butterfly - micro moth | Cnephasia stephensiana | Grey Tortrix | 287 | 2024 |
| moth or butterfly - micro moth | Cochylichroa atricapitana | Black-fronted Straw | 220 | 2025 |
| moth or butterfly - micro moth | Cochylidia implicitana | Chamomile Straw | 5 | 2018 |
| moth or butterfly - micro moth | Cochylidia rupicola | Agrimony Straw | 11 | 2014 |
| moth or butterfly - micro moth | Cochylimorpha straminea | Straw Conch | 90 | 2023 |
| moth or butterfly - micro moth | Cochylis flaviciliana | Pink-shaded Straw | 2 | 1996 |
| moth or butterfly - micro moth | Cochylis roseana | Rosy Straw | 66 | 2018 |
| moth or butterfly - micro moth | Coleophora | a Coleophora micro-moth (unidentified) | 48 | 2024 |
| moth or butterfly - micro moth | Coleophora adjunctella | Saltern Rush Case-bearer | 1 | 2011 |
| moth or butterfly - micro moth | Coleophora adspersella | Large Orache Case-bearer | 2 | 2014 |
| moth or butterfly - micro moth | Coleophora albella | Ragged-Robin Case-bearer | 1 | 1908 |
| moth or butterfly - micro moth | Coleophora albicosta | Gorse Case-bearer | 7 | 2014 |
| moth or butterfly - micro moth | Coleophora albidella | Sallow Pistol Case-bearer | 8 | 2022 |
| moth or butterfly - micro moth | Coleophora albitarsella | White-legged Case-bearer | 29 | 2024 |
| moth or butterfly - micro moth | Coleophora alcyonipennella | Small Clover Case-bearer | 10 | 2023 |
| moth or butterfly - micro moth | Coleophora alcyonipennella/frischella | a moth | 5 | 2021 |
| moth or butterfly - micro moth | Coleophora alticolella | Common Rush Case-bearer | 13 | 2020 |
| moth or butterfly - micro moth | Coleophora anatipennella | Pistol Case-bearer | 8 | 2015 |
| moth or butterfly - micro moth | Coleophora argentula | Yarrow Case-bearer | 6 | 2022 |
| moth or butterfly - micro moth | Coleophora artemisicolella | Mugwort Case-bearer | 1 | 2021 |
| moth or butterfly - micro moth | Coleophora asteris | Sea Aster Case-bearer | 1 | 2012 |
| moth or butterfly - micro moth | Coleophora atriplicis | Saltern Case-bearer | 3 | 2018 |
| moth or butterfly - micro moth | Coleophora badiipennella | Small Elm Case-bearer | 6 | 2022 |
| moth or butterfly - micro moth | Coleophora betulella | Birch Pistol Case-bearer | 4 | 2014 |
| moth or butterfly - micro moth | Coleophora binderella | Alder Case-bearer | 2 | 2021 |
| moth or butterfly - micro moth | Coleophora caespititiella | Buff Rush Case-bearer | 10 | 2022 |
| moth or butterfly - micro moth | Coleophora conyzae | Spikenard Case-bearer | 4 | 2013 |
| moth or butterfly - micro moth | Coleophora coracipennella | Blackthorn Case-bearer | 3 | 2020 |
| moth or butterfly - micro moth | Coleophora currucipennella | Wood Pistol Case-bearer | 3 | 2006 |
| moth or butterfly - micro moth | Coleophora deauratella | Purple-shot Case-bearer | 31 | 2024 |
| moth or butterfly - micro moth | Coleophora discordella | Lotus Case-bearer | 4 | 2016 |
| moth or butterfly - micro moth | Coleophora flavipennella | Tipped Oak Case-bearer | 16 | 2021 |
| moth or butterfly - micro moth | Coleophora follicularis | Agrimony Case-bearer | 6 | 2019 |
| moth or butterfly - micro moth | Coleophora frischella | Small Clover Case-bearer | 1 | 2008 |
| moth or butterfly - micro moth | Coleophora glaucicolella | Grey Rush Case-bearer | 8 | 2021 |
| moth or butterfly - micro moth | Coleophora gryphipennella | Rose Case-bearer | 18 | 2021 |
| moth or butterfly - micro moth | Coleophora ibipennella | Oak Pistol Case-bearer | 5 | 2013 |
| moth or butterfly - micro moth | Coleophora juncicolella | Least Case-bearer | 1 | 1908 |
| moth or butterfly - micro moth | Coleophora kuehnella | Cloaked Case-bearer | 1 | 2010 |
| moth or butterfly - micro moth | Coleophora laricella | Larch Case-bearer | 4 | 2022 |
| moth or butterfly - micro moth | Coleophora limosipennella | Elm Case-bearer | 13 | 2022 |
| moth or butterfly - micro moth | Coleophora lineolea | Woundwort Case-bearer | 32 | 2022 |
| moth or butterfly - micro moth | Coleophora lixella | Downland Case-bearer | 4 | 1999 |
| moth or butterfly - micro moth | Coleophora lusciniaepennella | Willow Case-bearer | 11 | 2014 |
| moth or butterfly - micro moth | Coleophora lutarea | Stitchwort Flower Moth | 9 | 2023 |
| moth or butterfly - micro moth | Coleophora lutipennella | Oak Case-bearer | 17 | 2022 |
| moth or butterfly - micro moth | Coleophora lutipennella/flavipennella | a micro-moth (Coleophora lutipennella or Coleophora flavipennella undetermined) | 4 | 2022 |
| moth or butterfly - micro moth | Coleophora maritimella | Sea Rush Case-bearer | 1 | 1997 |
| moth or butterfly - micro moth | Coleophora mayrella | Clothed Case-bearer | 51 | 2025 |
| moth or butterfly - micro moth | Coleophora milvipennis | Birch Case-bearer | 3 | 2021 |
| moth or butterfly - micro moth | Coleophora ochrea | Large Buff Case-bearer | 22 | 2022 |
| moth or butterfly - micro moth | Coleophora otidipennella | Wood-rush Case-bearer | 4 | 2021 |
| moth or butterfly - micro moth | Coleophora paripennella | Bronze Case-bearer | 9 | 2023 |
| moth or butterfly - micro moth | Coleophora peribenanderi | Pale Thistle Case-bearer | 16 | 2021 |
| moth or butterfly - micro moth | Coleophora potentillae | Potentilla Case-bearer | 5 | 2016 |
| moth or butterfly - micro moth | Coleophora prunifoliae | Sloe Case-bearer | 2 | 1985 |
| moth or butterfly - micro moth | Coleophora pyrrhulipennella | Heath Case-bearer | 2 | 2016 |
| moth or butterfly - micro moth | Coleophora salicorniae | Glasswort Case-bearer | 2 | 2011 |
| moth or butterfly - micro moth | Coleophora saturatella | Broom Case-bearer | 2 | 2016 |
| moth or butterfly - micro moth | Coleophora saxicolella | Orache Case-bearer | 13 | 2022 |
| moth or butterfly - micro moth | Coleophora serratella | Common Case-bearer | 25 | 2021 |
| moth or butterfly - micro moth | Coleophora spinella | Apple & Plum Case-bearer | 14 | 2020 |
| moth or butterfly - micro moth | Coleophora sternipennella | Goosefoot Case-bearer | 4 | 2022 |
| moth or butterfly - micro moth | Coleophora striatipennella | Hedge Case-bearer | 2 | 2016 |
| moth or butterfly - micro moth | Coleophora sylvaticella | Large Rush Case-bearer | 1 | 2003 |
| moth or butterfly - micro moth | Coleophora taeniipennella | Small Rush Case-bearer | 4 | 2014 |
| moth or butterfly - micro moth | Coleophora trifolii | Large Clover Case-bearer | 68 | 2024 |
| moth or butterfly - micro moth | Coleophora trochilella | Verge Case-bearer | 1 | 1908 |
| moth or butterfly - micro moth | Coleophora versurella | Pale Orache Case-bearer | 5 | 2022 |
| moth or butterfly - micro moth | Coleophora violacea | White-tipped Case-bearer | 1 | 1994 |
| moth or butterfly - micro moth | Coleophora virgaureae | Golden-rod Case-bearer | 3 | 2003 |
| moth or butterfly - micro moth | Commophila aeneana | Orange Beauty | 4 | 2022 |
| moth or butterfly - micro moth | Coptotriche marginea | Bordered Carl | 161 | 2023 |
| moth or butterfly - micro moth | Cosmopterix lienigiella | Pale Reed Beauty | 1 | 2015 |
| moth or butterfly - micro moth | Cosmopterix pulchrimella | Pellitory Beauty | 3 | 2023 |
| moth or butterfly - micro moth | Crambinae | a Crambinae species (unidentified) | 2 | 2014 |
| moth or butterfly - micro moth | Crambus | a Crambus species (unidentified) | 1 | 1991 |
| moth or butterfly - micro moth | Crambus lathoniellus | Hook-streak Grass-veneer | 557 | 2024 |
| moth or butterfly - micro moth | Crambus pascuella | White-banded Grass-moth | 160 | 2023 |
| moth or butterfly - micro moth | Crambus perlella | Satin Grass-veneer | 1286 | 2025 |
| moth or butterfly - micro moth | Crambus pratella | Scarce Grass-moth | 6 | 2017 |
| moth or butterfly - micro moth | Crambus uliginosellus | Marsh Grass-moth | 1 | 2023 |
| moth or butterfly - micro moth | Crassa tinctella | Plain Bark Moth | 5 | 2022 |
| moth or butterfly - micro moth | Crassa unitella | Golden-brown Tubic | 264 | 2025 |
| moth or butterfly - micro moth | Crocidosema plebejana | Tree-mallow Tortrix | 18 | 2023 |
| moth or butterfly - micro moth | Cryptoblabes bistriga | Double-striped Knot-horn | 28 | 2025 |
| moth or butterfly - micro moth | Cryptoblabes gnidiella | Pomegranate Moth | 1 | 2002 |
| moth or butterfly - micro moth | Cydalima perspectalis | Box Tree Moth | 1478 | 2025 |
| moth or butterfly - micro moth | Cydia | a Cydia species (unidentified) | 1 | 2010 |
| moth or butterfly - micro moth | Cydia amplana | Rusty Acorn Piercer | 11 | 2024 |
| moth or butterfly - micro moth | Cydia coniferana | Pine Bark Moth | 1 | 2000 |
| moth or butterfly - micro moth | Cydia fagiglandana | Beech Mast Piercer | 63 | 2024 |
| moth or butterfly - micro moth | Cydia nigricana | Pea Moth | 34 | 2023 |
| moth or butterfly - micro moth | Cydia pomonella | Codling Moth | 956 | 2024 |
| moth or butterfly - micro moth | Cydia servillana | Sallow Gall Moth | 2 | 2010 |
| moth or butterfly - micro moth | Cydia splendana | Marbled Piercer | 387 | 2024 |
| moth or butterfly - micro moth | Cydia strobilella | Spruce Seed Moth | 1 | 2019 |
| moth or butterfly - micro moth | Cydia ulicetana | Grey Gorse Piercer | 79 | 2023 |
| plant | Cakile maritima | Sea Rocket | 28 | 2020 |
| plant | Cakile maritima subsp. integrifolia | a crucifer | 17 | 1998 |
| plant | Calamagrostis epigejos | Wood Small-reed | 123 | 2018 |
| plant | Calendula arvensis | Field Marigold | 5 | 2017 |
| plant | Calendula officinalis | pot Marigold | 59 | 2023 |
| plant | Calla palustris | Bog Arum | 1 | 1984 |
| plant | Callitriche | Water-Starwort | 395 | 2024 |
| plant | Callitriche aggregate | a flowering plant | 38 | 2013 |
| plant | Callitriche brutia subsp. hamulata | Intermediate Water-Starwort | 8 | 2004 |
| plant | Callitriche obtusangula | Blunt-fruited Water-starwort | 65 | 2016 |
| plant | Callitriche platycarpa | Various-leaved Water-starwort | 40 | 2013 |
| plant | Callitriche stagnalis | Common Water-starwort | 227 | 2024 |
| plant | Callitriche stagnalis agg. | Common Water-starwort sens.lat. | 26 | 2006 |
| plant | Callitriche truncata | Short-leaved Water-starwort | 5 | 1999 |
| plant | Callitriche truncata subsp. occidentalis | a flowering plant | 2 | 1962 |
| plant | Calluna | a Calluna species (unidentified) | 1 | 2016 |
| plant | Calluna vulgaris | Heather | 123 | 2023 |
| plant | Calocedrus decurrens | Californian Incense-cedar | 12 | 2015 |
| plant | Caltha palustris | Marsh Marigold | 660 | 2024 |
| plant | Calystegia | Bindweed | 43 | 2023 |
| plant | Calystegia pulchra | Hairy Bindweed | 10 | 2011 |
| plant | Calystegia sepium | Hedge Bindweed | 1237 | 2024 |
| plant | Calystegia sepium sens. lat. | Hedge Bindweed (sens.lat.) | 10 | 2014 |
| plant | Calystegia sepium subsp. sepium | Great Bindweed | 1679 | 2017 |
| plant | Calystegia sepium x silvatica = C. x lucana | a bindweed | 35 | 2011 |
| plant | Calystegia silvatica | Large Bindweed | 851 | 2024 |
| plant | Calystegia silvatica subsp. disjuncta | a flowering plant | 1 | 2015 |
| plant | Calystegia silvatica subsp. silvatica var. quinquepartita | a bindweed | 1 | 2013 |
| plant | Calystegia soldanella | Sea Bindweed | 8 | 2008 |
| plant | Calystegia sp. or Convolvulus sp. (unidentified bindweed) | a bindweed (unidentified) | 64 | 2023 |
| plant | Calystegia subsp. sepium forma colorata | a bindweed | 1 | 1999 |
| plant | Camassia | a Camassia species (unidentified) | 3 | 2023 |
| plant | Camassia leichtlinii | a flowering plant | 4 | 2023 |
| plant | Camelina alyssum | a gold-of-pleasure | 1 | 1937 |
| plant | Camelina microcarpa | Lesser Gold-of-pleasure | 4 | 1961 |
| plant | Camelina sativa | Gold-of-pleasure | 6 | 2009 |
| plant | Campanula | Indet. Bellflower | 12 | 2017 |
| plant | Campanula alliariifolia | Cornish Bellflower | 3 | 2000 |
| plant | Campanula glomerata | Clustered Bellflower | 87 | 2021 |
| plant | Campanula latifolia | Giant Bellflower | 9 | 2016 |
| plant | Campanula medium | Canterbury-bell | 1 | 1984 |
| plant | Campanula patula | Spreading Bellflower | 20 | 2011 |
| plant | Campanula persicifolia | Peach-leaved Bellflower | 4 | 2010 |
| plant | Campanula portenschlagiana | Adria Bellflower | 464 | 2024 |
| plant | Campanula poscharskyana | Trailing Bellflower | 571 | 2024 |
| plant | Campanula rapunculoides | Creeping Bellflower | 9 | 2018 |
| plant | Campanula rotundifolia | Harebell | 451 | 2025 |
| plant | Campanula trachelium | Nettle-leaved Bellflower | 224 | 2024 |
| plant | Cannabis sativa | Hemp | 19 | 2014 |
| plant | Capsella bursa-pastoris | Shepherd's-purse | 3569 | 2024 |
| plant | Capsicum annuum | Sweet Pepper | 2 | 1930 |
| plant | Caragana | a Caragana species (unidentified) | 1 | 2009 |
| plant | Cardamine | Bitter-Cress | 44 | 2023 |
| plant | Cardamine amara | Large Bitter-cress | 6 | 2018 |
| plant | Cardamine bulbifera | Coralroot | 17 | 2019 |
| plant | Cardamine corymbosa | New Zealand Bitter-cress | 5 | 2016 |
| plant | Cardamine flexuosa | Wavy Bitter-cress | 1445 | 2024 |
| plant | Cardamine flexuosa x pratensis = C. x fringsii | a bitter-cress | 2 | 2000 |
| plant | Cardamine hirsuta | Hairy Bitter-cress | 2587 | 2024 |
| plant | Cardamine impatiens | Narrow-leaved Bitter-cress | 50 | 2023 |
| plant | Cardamine pratensis | Cuckoo-flower | 3035 | 2025 |
| plant | Carduus crispus | Welted Thistle | 906 | 2024 |
| plant | Carduus crispus subsp. multiflorus | Broad-winged Thistle | 6 | 2016 |
| plant | Carduus crispus x nutans = C. x stangii | a thistle | 2 | 1995 |
| plant | Carduus hamulosus | a flowering plant | 1 | 1938 |
| plant | Carduus macrocephalus | Giant Thistle | 1 | 1938 |
| plant | Carduus nutans | Musk Thistle | 480 | 2024 |
| plant | Carduus pycnocephalus | Plymouth Thistle | 4 | 1937 |
| plant | Carduus tenuiflorus | Slender Thistle | 48 | 2014 |
| plant | Carex | Sedge | 622 | 2024 |
| plant | Carex acuta | Slender Tufted-sedge | 17 | 2011 |
| plant | Carex acuta x elata = C. x prolixa | a sedge | 1 | 1913 |
| plant | Carex acutiformis | Lesser Pond-sedge | 325 | 2024 |
| plant | Carex arenaria | Sand Sedge | 71 | 2019 |
| plant | Carex binervis | Green-ribbed Sedge | 3 | 2015 |
| plant | Carex caryophyllea | Spring Sedge | 465 | 2024 |
| plant | Carex comans | New Zealand Hair Sedge | 1 | 2017 |
| plant | Carex demissa | Common Yellow Sedge | 136 | 2018 |
| plant | Carex digitata | Fingered Sedge | 24 | 2012 |
| plant | Carex distans | Distant Sedge | 69 | 2015 |
| plant | Carex disticha | Brown Sedge | 151 | 2019 |
| plant | Carex divisa | Divided Sedge | 2 | 1921 |
| plant | Carex divulsa | a Grey Sedge | 443 | 2024 |
| plant | Carex divulsa subsp. divulsa | Grey Sedge | 143 | 2019 |
| plant | Carex divulsa subsp. leersii | Leers' Sedge | 6 | 2016 |
| plant | Carex echinata | Star Sedge | 53 | 2019 |
| plant | Carex elata | Tufted Sedge | 14 | 2009 |
| plant | Carex extensa | Long-bracted Sedge | 57 | 2023 |
| plant | Carex flacca | Glaucous Sedge | 2619 | 2024 |
| plant | Carex flava × hostiana | a sedge | 1 | 1921 |
| plant | Carex hirta | Hairy Sedge | 1581 | 2024 |
| plant | Carex hostiana | Tawny Sedge | 49 | 2019 |
| plant | Carex hostiana x viridula s.l. | a sedge | 1 | 1998 |
| plant | Carex humilis | Dwarf Sedge | 80 | 2013 |
| plant | Carex laevigata | Smooth-stalked Sedge | 10 | 2011 |
| plant | Carex lepidocarpa | Long-stalked Yellow Sedge | 39 | 2018 |
| plant | Carex leporina | Oval Sedge | 206 | 2024 |
| plant | Carex montana | Soft-leaved Sedge | 7 | 2008 |
| plant | Carex muricata | Prickly Sedge | 3 | 2004 |
| plant | Carex muricata subsp. pairae | Small-fruited Prickly-sedge | 16 | 2012 |
| plant | Carex nigra | Common Sedge | 187 | 2021 |
| plant | Carex otrubae | False Fox-sedge | 1408 | 2024 |
| plant | Carex otrubae x remota = C. x pseudoaxillaris | a sedge | 3 | 1992 |
| plant | Carex pallescens | Pale Sedge | 22 | 2010 |
| plant | Carex panicea | Carnation Sedge | 257 | 2024 |
| plant | Carex paniculata | Greater Tussock-sedge | 10 | 2006 |
| plant | Carex pendula | Pendulous Sedge | 2294 | 2025 |
| plant | Carex pilulifera | Pill Sedge | 43 | 2019 |
| plant | Carex pseudocyperus | Cyperus Sedge | 199 | 2018 |
| plant | Carex pulicaris | Flea Sedge | 46 | 2019 |
| plant | Carex remota | Remote Sedge | 759 | 2024 |
| plant | Carex riparia | Great Pond-sedge | 520 | 2024 |
| plant | Carex rostrata | Bottle Sedge | 18 | 2018 |
| plant | Carex rupestris | Rock Sedge | 1 | 1989 |
| plant | Carex spicata | Spiked Sedge | 432 | 2023 |
| plant | Carex strigosa | Thin-spiked Wood-sedge | 192 | 2023 |
| plant | Carex sylvatica | Wood-sedge | 1651 | 2024 |
| plant | Carex vesicaria | Bladder-sedge | 7 | 2011 |
| plant | Carex viridula | Yellow Sedge | 5 | 2012 |
| plant | Carex viridula subsp. viridula | Small-fruited Yellow Sedge | 2 | 2004 |
| plant | Carex vulpinoidea | American Fox-sedge | 1 | 1932 |
| plant | Carlina vulgaris | Carline Thistle | 332 | 2024 |
| plant | Carpinus | a Carpinus species (unidentified) | 4 | 2018 |
| plant | Carpinus betulus | Hornbeam | 828 | 2024 |
| plant | Carrichtera annua | Cress Rocket | 2 | 2013 |
| plant | Carthamus lanatus | Downy Safflower | 2 | 1937 |
| plant | Carthamus oxyacanthus | a flowering plant | 2 | 1938 |
| plant | Carthamus tinctorius | Safflower | 1 | 2010 |
| plant | Carum carvi | Caraway | 8 | 2013 |
| plant | Castanea | a Castanea species (unidentified) | 2 | 2009 |
| plant | Castanea sativa | Sweet Chestnut | 652 | 2024 |
| plant | Catabrosa aquatica | Whorl-grass | 41 | 2013 |
| plant | Catalpa | a catalpa (unidentified) | 17 | 2000 |
| plant | Catalpa bignonioides | Indian Bean-tree | 6 | 2015 |
| plant | Catapodium marinum | Sea Fern-grass | 73 | 2019 |
| plant | Catapodium rigidum | Fern-grass | 437 | 2024 |
| plant | Caucalis platycarpos | Small Bur-parsley | 7 | 1939 |
| plant | Ceanothus | a ceanothus shrub (unidentified) | 3 | 2023 |
| plant | Cedrus | Cedar | 15 | 2023 |
| plant | Cedrus atlantica | Atlas Cedar | 135 | 2023 |
| plant | Cedrus deodara | Deodar | 72 | 2023 |
| plant | Cedrus libani | Cedar of Lebanon | 79 | 2020 |
| plant | Celosia trigyna | a flowering plant | 1 | 1928 |
| plant | Celtis occidentalis | Common Hackberry | 1 | 2015 |
| plant | Cenchrus americanus | Pearl Millet | 5 | 1958 |
| plant | Centaurea | Knapweed | 66 | 2023 |
| plant | Centaurea calcitrapa | Red Star-thistle | 1 | 1926 |
| plant | Centaurea cyanus | Cornflower | 47 | 2019 |
| plant | Centaurea debeauxii | Slender Knapweed | 7 | 2014 |
| plant | Centaurea debeauxii subsp. nemoralis var. nemoralis | a flowering plant | 2 | 1992 |
| plant | Centaurea debeauxii x jacea = C. x moncktonii | Hybrid Knapweed | 1 | 2000 |
| plant | Centaurea hyalolepis | Eastern Star-thistle | 2 | 1938 |
| plant | Centaurea iberica | Iberian Star-thistle | 2 | 1939 |
| plant | Centaurea jacea | Brown Knapweed | 4 | 2021 |
| plant | Centaurea maculosa | Spotted Knapweed | 2 | 1930 |
| plant | Centaurea montana | Perennial Cornflower | 38 | 2023 |
| plant | Centaurea nigra sens. lat. | Common Knapweed | 4439 | 2024 |
| plant | Centaurea nigra subsp. nigra | Common Knapweed | 6 | 2021 |
| plant | Centaurea paniculata | Jersey Knapweed | 1 | 1934 |
| plant | Centaurea scabiosa | Greater Knapweed | 960 | 2024 |
| plant | Centaurea solstitialis | Yellow Star-thistle | 1 | 1956 |
| plant | Centaurium | Centaury | 10 | 2023 |
| plant | Centaurium erythraea | Common Centaury | 1114 | 2024 |
| plant | Centaurium erythraea var. erythraea | a flowering plant | 1 | 1988 |
| plant | Centaurium littorale | Seaside Centaury | 3 | 1956 |
| plant | Centaurium pulchellum | Lesser Centaury | 24 | 2008 |
| plant | Centranthus ruber | Red Valerian | 2054 | 2025 |
| plant | Cephalanthera damasonium | White Helleborine | 40 | 2023 |
| plant | Cephalanthera longifolia | Narrow-leaved Helleborine | 3 | 1915 |
| plant | Cephalaria gigantea | Giant Scabious | 3 | 2008 |
| plant | Cephalaria syriaca | a flowering plant | 1 | 1931 |
| plant | Cerastium | Mouse-Ear | 22 | 2023 |
| plant | Cerastium arvense | Field Mouse-ear | 17 | 2010 |
| plant | Cerastium diffusum | Sea Mouse-ear | 91 | 2016 |
| plant | Cerastium fontanum | Common Mouse-ear | 5525 | 2024 |
| plant | Cerastium fontanum subsp. holosteoides | a common mouse-ear | 36 | 2004 |
| plant | Cerastium fontanum subsp. vulgare | a common mouse-ear | 4 | 2016 |
| plant | Cerastium glomeratum | Sticky Mouse-ear | 1432 | 2024 |
| plant | Cerastium pumilum | Dwarf Mouse-ear | 81 | 2023 |
| plant | Cerastium semidecandrum | Little Mouse-ear | 138 | 2023 |
| plant | Cerastium tomentosum | Snow-in-summer | 290 | 2024 |
| plant | Ceratocapnos claviculata | Climbing Corydalis | 22 | 2011 |
| plant | Ceratochloa carinata | California Brome | 1 | 2010 |
| plant | Ceratochloa cathartica | Rescue Brome | 7 | 2015 |
| plant | Ceratophyllaceae | a Ceratophyllaceae species (unidentified) | 3 | 1988 |
| plant | Ceratophyllum | a Ceratophyllum species (unidentified) | 5 | 2014 |
| plant | Ceratophyllum demersum | Rigid Hornwort | 305 | 2024 |
| plant | Ceratophyllum submersum | Soft Hornwort | 55 | 2013 |
| plant | Cercidiphyllum | a Cercidiphyllum species (unidentified) | 1 | 2015 |
| plant | Cercidiphyllum japonicum | a flowering plant | 3 | 2000 |
| plant | Cercis siliquastrum | Judas Tree | 16 | 2019 |
| plant | Cerinthe major | Greater Honeywort | 7 | 2020 |
| plant | Chaenomeles japonica | Japanese Quince | 1 | 2018 |
| plant | Chaenomeles speciosa | Japanese Quince | 2 | 2002 |
| plant | Chaenorhinum minus | Small Toadflax | 254 | 2024 |
| plant | Chaenorhinum origanifolium | Malling Toadflax | 2 | 2012 |
| plant | Chaenostoma cordatum | Bacopa | 4 | 2016 |
| plant | Chaerophyllum temulum | Rough Chervil | 1402 | 2024 |
| plant | Chamaecyparis | a Chamaecyparis species (unidentified) | 6 | 2023 |
| plant | Chamaemelum nobile | Chamomile | 12 | 2017 |
| plant | Chamaenerion angustifolium | Rosebay Willowherb | 2743 | 2024 |
| plant | Chelidonium majus | Greater Celandine | 655 | 2024 |
| plant | Chenopodiastrum hybridum | Maple-leaved Goosefoot | 1 | 1938 |
| plant | Chenopodiastrum murale | Nettle-leaved Goosefoot | 14 | 2022 |
| plant | Chenopodium | Indet. Goosefoot | 12 | 2023 |
| plant | Chenopodium album | Fat-hen | 563 | 2024 |
| plant | Chenopodium album agg. | Fat-hen (agg.) | 997 | 2011 |
| plant | Chenopodium album var. lanceolatum | a goosefoot | 1 | 1927 |
| plant | Chenopodium album x berlandieri = C. x variabile | a goosefoot | 1 | 1935 |
| plant | Chenopodium berlandieri | Pitseed Goosefoot | 5 | 1928 |
| plant | Chenopodium borbasioides | a flowering plant | 2 | 1957 |
| plant | Chenopodium diversifolium | a goosefoot | 1 | 1933 |
| plant | Chenopodium ficifolium | Fig-leaved Goosefoot | 150 | 2016 |
| plant | Chenopodium giganteum | Tree Spinnach | 5 | 2018 |
| plant | Chenopodium hircinum | Foetid Goosefoot | 10 | 1934 |
| plant | Chenopodium missouriense | Soya-bean Goosefoot | 4 | 1957 |
| plant | Chenopodium opulifolium | Grey Goosefoot | 7 | 1938 |
| plant | Chenopodium pratericola | Slimleaf Goosefoot | 5 | 1957 |
| plant | Chenopodium probstii | Probst's Goosefoot | 2 | 1997 |
| plant | Chenopodium strictum | Striped Goosefoot | 2 | 1930 |
| plant | Chimonanthus praecox | Wintersweet | 1 | 1984 |
| plant | Chloris virgata | Feathery Rhodes-grass | 1 | 1959 |
| plant | Choisya ternata | Mexican Orange | 11 | 2023 |
| plant | Chorispora tenella | a flowering plant | 2 | 1931 |
| plant | Chrysosplenium alternifolium | Alternate-leaved Golden-saxifrage | 18 | 2017 |
| plant | Chrysosplenium oppositifolium | Opposite-leaved Golden-saxifrage | 600 | 2024 |
| plant | Cicer arietinum | Chick Pea | 1 | 1924 |
| plant | Cicerbita macrophylla | Common Blue-sow-thistle | 12 | 2018 |
| plant | Cicerbita macrophylla subsp. uralensis | Common Blue-Sow-Thistle | 11 | 1999 |
| plant | Cichorium intybus | Chicory | 178 | 2023 |
| plant | Circaea lutetiana | Enchanter's-nightshade | 2641 | 2024 |
| plant | Cirsium | Thistle | 52 | 2023 |
| plant | Cirsium acaule | Dwarf Thistle | 1213 | 2021 |
| plant | Cirsium acaule x vulgare = C. x sabaudum | a thistle | 1 | 2004 |
| plant | Cirsium arvense | Creeping Thistle | 7768 | 2024 |
| plant | Cirsium arvense var. incanum | Creeping Thistle | 4 | 2021 |
| plant | Cirsium dissectum | Meadow Thistle | 142 | 2025 |
| plant | Cirsium dissectum x palustre = C. x forsteri | a thistle | 2 | 1998 |
| plant | Cirsium eriophorum | Woolly Thistle | 1163 | 2023 |
| plant | Cirsium heterophyllum | Melancholy Thistle | 1 | 1994 |
| plant | Cirsium oleraceum | Cabbage Thistle | 2 | 1982 |
| plant | Cirsium palustre | Marsh Thistle | 2265 | 2025 |
| plant | Cirsium rivulare | Brook Thistle | 1 | 2025 |
| plant | Cirsium sp. or Carlina sp. or Onopordum sp. or Silybum sp. or Carduus sp. (unidentified thistle) | a thistle (unidentified) | 151 | 2023 |
| plant | Cirsium tuberosum | Tuberous Thistle | 1 | 1996 |
| plant | Cirsium vulgare | Spear Thistle | 6280 | 2024 |
| plant | Cistus | a Cistus species (unidentified) | 2 | 2015 |
| plant | Citrullus lanatus | Water Melon | 3 | 1996 |
| plant | Cladium mariscus | Great Fen-sedge | 1 | 1921 |
| plant | Clarkia amoena | Godetia | 1 | 1985 |
| plant | Claytonia perfoliata | Spring Beauty | 15 | 2023 |
| plant | Claytonia sibirica | Pink Purslane | 2 | 2019 |
| plant | Clematis | a clematis (unidentified) | 28 | 2022 |
| plant | Clematis armandii | a clematis | 2 | 2013 |
| plant | Clematis flammula | Virgin's-bower | 2 | 1936 |
| plant | Clematis montana | Himalayan Clematis | 6 | 2019 |
| plant | Clematis tangutica | Orange-peel Clematis | 2 | 2010 |
| plant | Clematis vitalba | Traveller's Joy | 4946 | 2024 |
| plant | Clematis viticella | Purple Clematis | 1 | 1999 |
| plant | Clerodendrum | a Clerodendrum species (unidentified) | 9 | 2011 |
| plant | Clinopodium | Calamint Cultivar | 9 | 2017 |
| plant | Clinopodium acinos | Basil Thyme | 75 | 2023 |
| plant | Clinopodium ascendens | Common Calamint | 287 | 2020 |
| plant | Clinopodium menthifolium | Wood Calamint | 10 | 2002 |
| plant | Clinopodium vulgare | Wild Basil | 827 | 2024 |
| plant | Cochlearia anglica | English Scurvygrass | 282 | 2023 |
| plant | Cochlearia danica | Danish Scurvygrass | 924 | 2024 |
| plant | Cochlearia officinalis | Common Scurvygrass | 100 | 2023 |
| plant | Cochlearia officinalis agg. | Common Scurvygrass sens.lat. | 7 | 2002 |
| plant | Coincya monensis subsp. cheiranthos | Wallflower Cabbage | 4 | 2003 |
| plant | Colchicum autumnale | Meadow Saffron | 126 | 2023 |
| plant | Collomia linearis | a flowering plant | 2 | 1924 |
| plant | Colutea | a Colutea species (unidentified) | 1 | 2013 |
| plant | Colutea arborescens | Bladder-senna | 10 | 2010 |
| plant | Comarum palustre | Marsh Cinquefoil | 8 | 2022 |
| plant | Commelina communis | a flowering plant | 1 | 1931 |
| plant | Conium maculatum | Hemlock | 1548 | 2024 |
| plant | Conopodium | a Conopodium species (unidentified) | 1 | 2001 |
| plant | Conopodium majus | Pignut | 1759 | 2024 |
| plant | Conringia orientalis | Hare's-ear Mustard | 6 | 1954 |
| plant | Consolida ajacis | Larkspur | 5 | 1987 |
| plant | Consolida regalis | Forking Larkspur | 2 | 1939 |
| plant | Convallaria majalis | Lily of the Valley | 31 | 2023 |
| plant | Convolvulus | a convolvulus bindweed (unidentified) | 75 | 2021 |
| plant | Convolvulus arvensis | Field Bindweed | 3937 | 2024 |
| plant | Convolvulus arvensis var. stonestreetii | Field Bindweed | 1 | 2021 |
| plant | Convolvulus stachydifolius | a flowering plant | 1 | 1937 |
| plant | Corchorus olitorius | Tossa Jute | 1 | 1932 |
| plant | Cordyline | a Cordyline species (unidentified) | 1 | 2019 |
| plant | Cordyline australis | Cabbage-palm | 95 | 2023 |
| plant | Coriandrum sativum | Coriander | 6 | 2009 |
| plant | Cornus | a dogwood (unidentified) | 122 | 2023 |
| plant | Cornus alba | White Dogwood | 29 | 2019 |
| plant | Cornus capitata | Bentham's Dogwood | 1 | 2006 |
| plant | Cornus controversa variegata | Table Dogwood | 1 | 2015 |
| plant | Cornus mas | Cornelian-cherry | 15 | 2007 |
| plant | Cornus sanguinea | Dogwood | 5818 | 2024 |
| plant | Cornus sericea | Red-osier Dogwood | 9 | 2023 |
| plant | Coronilla scorpioides | Annual Scorpion-vetch | 2 | 1930 |
| plant | Cortaderia | a Cortaderia species (unidentified) | 2 | 2009 |
| plant | Cortaderia selloana | Pampas Grass | 28 | 2019 |
| plant | Corydalis | a corydalis (unidentified) | 3 | 2013 |
| plant | Corydalis cheilanthifolia | Fern-leaved Corydalis | 3 | 2009 |
| plant | Corydalis solida | Bird-in-a-bush | 1 | 2010 |
| plant | Corylus | a Hazel (unidentified) | 34 | 2024 |
| plant | Corylus avellana | Hazel | 10853 | 2025 |
| plant | Corylus colurna | Turkish Hazel | 17 | 2023 |
| plant | Corylus maxima | Filbert | 2 | 2023 |
| plant | Cosmos bipinnatus | Mexican Aster | 3 | 2008 |
| plant | Cota austriaca | Austrian Chamomile | 3 | 2023 |
| plant | Cota tinctoria | Yellow Chamomile | 4 | 2000 |
| plant | Cotinus coggygria | Smoke-tree | 57 | 2019 |
| plant | Cotoneaster | a cotoneaster (unidentified) | 365 | 2024 |
| plant | Cotoneaster acuminatus | a Cotoneaster | 1 | 2024 |
| plant | Cotoneaster bullatus | Hollyberry Cotoneaster | 13 | 2024 |
| plant | Cotoneaster cambricus | Wild Cotoneaster | 1 | 2012 |
| plant | Cotoneaster dielsianus | Diel's Cotoneaster | 3 | 1995 |
| plant | Cotoneaster divaricatus | Spreading Cotoneaster | 3 | 2019 |
| plant | Cotoneaster franchetii | Franchet's Cotoneaster | 21 | 2023 |
| plant | Cotoneaster frigidus | Tree Cotoneaster | 26 | 2022 |
| plant | Cotoneaster frigidus x salicifolius = C. x watereri | Waterer's Cotoneaster | 62 | 2014 |
| plant | Cotoneaster hjelmqvistii | Hjelmqvist's Cotoneaster | 1 | 1998 |
| plant | Cotoneaster horizontalis | Wall Cotoneaster | 369 | 2024 |
| plant | Cotoneaster horizontalis agg. | a Wall Cotoneaster (agg.) | 46 | 2011 |
| plant | Cotoneaster integrifolius | Entire-Leaved Cotoneaster | 56 | 2006 |
| plant | Cotoneaster lacteus | Late Cotoneaster | 8 | 2014 |
| plant | Cotoneaster microphyllus | Small-leaved Cotoneaster | 2 | 1997 |
| plant | Cotoneaster microphyllus agg. | Small-Leaved Cotoneaster | 8 | 2003 |
| plant | Cotoneaster prostratus | Procumbent Cotoneaster | 2 | 2014 |
| plant | Cotoneaster rehderi | Bullate Cotoneaster | 3 | 2006 |
| plant | Cotoneaster rotundifolius | Distichous Cotoneaster | 4 | 2009 |
| plant | Cotoneaster salicifolius | Willow-leaved Cotoneaster | 5 | 2013 |
| plant | Cotoneaster salicifolius x dammeri 'Hybridus Pendulus' | Weeping Cotoneaster | 1 | 2014 |
| plant | Cotoneaster simonsii | Himalayan Cotoneaster | 125 | 2022 |
| plant | Cotoneaster sternianus | Stern's Cotoneaster | 9 | 2016 |
| plant | Cotoneaster vilmorinianus | Vilmorin's Cotoneaster | 3 | 1995 |
| plant | Cotula coronopifolia | Buttonweed | 2 | 1990 |
| plant | Crambe maritima | Sea-kale | 1 | 2002 |
| plant | Crassula helmsii | New Zealand Pigmyweed | 35 | 2023 |
| plant | Crataegus | a Crataegus species (unidentified) | 31 | 2023 |
| plant | Crataegus crus-galli | Cockspur-thorn | 2 | 2002 |
| plant | Crataegus crus-galli x pubescens = C. x lavalleei | Hybrid Cockspur-thorn | 37 | 2016 |
| plant | Crataegus laevigata | Midland Hawthorn | 38 | 2021 |
| plant | Crataegus laevigata x monogyna = C. x media | Hybrid Hawthorn | 19 | 2016 |
| plant | Crataegus monogyna | Hawthorn | 17166 | 2024 |
| plant | Crataegus orientalis | Oriental Hawthorn | 1 | 2000 |
| plant | Crataegus persimilis | Broad-leaved Cockspur-thorn | 8 | 2014 |
| plant | Crepis | a hawk's-beard (unidentified) | 26 | 2023 |
| plant | Crepis biennis | Rough Hawk's-beard | 160 | 2023 |
| plant | Crepis capillaris | Smooth Hawk's-beard | 2483 | 2024 |
| plant | Crepis capillaris var. agrestis | a flowering plant | 1 | 2012 |
| plant | Crepis foetida | Stinking Hawk's-beard | 1 | 1939 |
| plant | Crepis setosa | Bristly Hawk's-beard | 4 | 2001 |
| plant | Crepis vesicaria | Beaked Hawk's-beard | 1888 | 2024 |
| plant | Crepis vesicaria subsp. taraxacifolia | a flowering plant | 6 | 2022 |
| plant | Crithmum maritimum | Rock Samphire | 158 | 2023 |
| plant | Crithopsis delileana | a flowering plant | 1 | 1937 |
| plant | Crocosmia | Montbretia | 3 | 2022 |
| plant | Crocosmia aurea x pottsii = C. x crocosmiiflora | Montbretia | 159 | 2022 |
| plant | Crocosmia paniculata | Aunt-Eliza | 1 | 2015 |
| plant | Crocosmia pottsii | Pott's Monbretia | 2 | 2009 |
| plant | Crocus | a crocus (unidentified) | 9 | 2020 |
| plant | Crocus angustifolius x flavus = C. x luteus | Yellow Crocus | 4 | 2013 |
| plant | Crocus flavus | Yellow Crocus | 7 | 2000 |
| plant | Crocus neapolitanus | a flowering plant | 3 | 2013 |
| plant | Crocus nudiflorus | Autumn Crocus | 18 | 2021 |
| plant | Crocus tommasinianus | Early Crocus | 22 | 2018 |
| plant | Crocus vernus agg. | Spring Crocus | 19 | 2017 |
| plant | Cruciata laevipes | Crosswort | 132 | 2023 |
| plant | Cryptomeria japonica | Japanese Red-cedar | 21 | 2015 |
| plant | Cucumis melo | Melon | 3 | 1996 |
| plant | Cucumis sativus | Cucumber | 3 | 2013 |
| plant | Cucurbita maxima | Pumpkin | 2 | 2020 |
| plant | Cucurbita pepo | Marrow | 6 | 2013 |
| plant | Cuminum cyminum | Cumin | 1 | 1937 |
| plant | Cupressaceae | Cypress | 24 | 2024 |
| plant | Cupressus | a Cupressus species (unidentified) | 31 | 2019 |
| plant | Cupressus lawsoniana | Lawson's Cypress | 241 | 2024 |
| plant | Cupressus lawsoniana 'Erecta Viridis' | Lawson Cypress Erecta | 1 | 2015 |
| plant | Cupressus macrocarpa | Monterey Cypress | 72 | 2016 |
| plant | Cupressus macrocarpa x nootkatensis = C. x leylandii | Leyland Cypress | 171 | 2021 |
| plant | Cupressus nootkatensis | Nootka Cypress | 3 | 2000 |
| plant | Cupressus pisifera | Sawara Cypress | 14 | 2013 |
| plant | Cupressus sempervirens | Italian Cypress | 18 | 2015 |
| plant | Cuscuta | a Cuscuta species (unidentified) | 1 | 2011 |
| plant | Cuscuta campestris | Yellow Dodder | 2 | 1999 |
| plant | Cuscuta epithymum | Dodder | 20 | 2011 |
| plant | Cuscuta europaea | Greater Dodder | 157 | 2018 |
| plant | Cyclamen | a cyclamen (unidentified) | 11 | 2023 |
| plant | Cyclamen hederifolium | Cyclamen | 94 | 2020 |
| plant | Cyclamen persicum | Florist's Cyclamen | 2 | 2009 |
| plant | Cyclamen repandum | Spring Sowbread | 9 | 2023 |
| plant | Cyclospermum leptophyllum | Slender Celery | 2 | 1961 |
| plant | Cydonia oblonga | Quince | 12 | 2017 |
| plant | Cymbalaria muralis | Ivy-leaved Toadflax | 3373 | 2024 |
| plant | Cymbalaria muralis subsp. muralis | an ivy-leaved toadflax | 12 | 2014 |
| plant | Cymbalaria pallida | Italian Toadflax | 1 | 2016 |
| plant | Cynara cardunculus | Globe Artichoke | 14 | 2020 |
| plant | Cynodon dactylon | Bermuda-grass | 31 | 2011 |
| plant | Cynoglossum officinale | Hound's-tongue | 150 | 2019 |
| plant | Cynosurus cristatus | Crested Dog's-tail | 4470 | 2025 |
| plant | Cynosurus echinatus | Rough Dog's-tail | 1 | 1916 |
| plant | Cyperaceae | a Cyperaceae species (unidentified) | 2 | 2021 |
| plant | Cyperus alternifolius | Umbrella Plant | 1 | 2022 |
| plant | Cyperus eragrostis | Pale Galingale | 7 | 2018 |
| plant | Cyperus fuscus | Brown Galingale | 57 | 2015 |
| plant | Cyperus involucratus | a flowering plant | 1 | 2016 |
| plant | Cyperus longus | Galingale | 48 | 2022 |
| plant | Cyrtomium | a Cyrtomium species (unidentified) | 1 | 2009 |
| plant | Cyrtomium falcatum | House Holly-fern | 3 | 2014 |
| plant | Cyrtomium fortunei | Fortune's Holly-fern | 4 | 2020 |
| plant | Cystopteris fragilis | Brittle Bladder-fern | 71 | 2021 |
| plant | Cytisus | a Cytisus species (unidentified) | 1 | 2016 |
| plant | Cytisus battandieri | Pineapple Broom | 1 | 2013 |
| plant | Cytisus multiflorus x purgans = C. x praecox | Allgold Broom | 1 | 2018 |
| plant | Cytisus scoparius | Broom | 164 | 2023 |
| plant | Cytisus scoparius subsp. scoparius | a broom | 144 | 2013 |
| reptile | Colubridae sp. or Viperidae sp. (unidentified) | a snake (unidentified) | 10 | 2016 |
| sea-fan, sea anemone or jellyfish | Clava multicornis | Club-headed Hydroid | 4 | 1976 |
| sea-fan, sea anemone or jellyfish | Clytia hemisphaerica | a Sea-fan/Sea Anemone/Jellyfish | 1 | 1939 |
| sea-fan, sea anemone or jellyfish | Cylista troglodytes | Cave-dwelling Anemone | 1 | 1938 |
| slime mould | Calomyxa metallica | a slime mould | 4 | 2008 |
| slime mould | Ceratiomyxa | a Ceratiomyxa slime mould (unidentified) | 1 | 2012 |
| slime mould | Ceratiomyxa fruticulosa | a slime mould | 22 | 2023 |
| slime mould | Ceratiomyxa fruticulosa var. fruticulosa | a slime mould | 30 | 2013 |
| slime mould | Comatricha nigra | a slime mould | 5 | 2008 |
| slime mould | Craterium leucocephalum var. leucocephalum | a slime mould | 1 | 2015 |
| slime mould | Craterium minutum | a slime mould | 5 | 2014 |
| slime mould | Cribraria argillacea | a slime mould | 4 | 2017 |
| slime mould | Cribraria aurantiaca | a slime mould | 1 | 2008 |
| slime mould | Cribraria cancellata | a slime mould | 1 | 2016 |
| slime mould | Cribraria cancellata var. cancellata | a slime mould | 1 | 2008 |
| slime mould | Cribraria minutissima | a slime mould | 1 | 2016 |
| spider | Centromerita bicolor | a money spider | 17 | 2019 |
| spider | Centromerus cavernarum | a money spider | 1 | 2002 |
| spider | Centromerus dilutus | a money spider | 8 | 1998 |
| spider | Centromerus sylvaticus | a money spider | 2 | 2019 |
| spider | Ceratinella brevipes | a money spider | 2 | 2003 |
| spider | Cheiracanthium erraticum | a foliage spider | 7 | 2016 |
| spider | Cheiracanthium virescens | a foliage spider | 2 | 1989 |
| spider | Cicurina cicur | a cobweb spider | 4 | 1990 |
| spider | Clubiona | a foliage spider (unidentified) | 13 | 2023 |
| spider | Clubiona brevipes | a foliage spider | 15 | 2014 |
| spider | Clubiona comta | a foliage spider | 20 | 2023 |
| spider | Clubiona corticalis | a foliage spider | 7 | 2009 |
| spider | Clubiona diversa | a foliage spider | 2 | 1985 |
| spider | Clubiona lutescens | a foliage spider | 7 | 1999 |
| spider | Clubiona neglecta sensu lato | a foliage spider | 2 | 1989 |
| spider | Clubiona pallidula | a foliage spider | 2 | 1989 |
| spider | Clubiona phragmitis | a foliage spider | 11 | 1999 |
| spider | Clubiona reclusa | a foliage spider | 14 | 2013 |
| spider | Clubiona stagnatilis | a foliage spider | 4 | 1998 |
| spider | Clubiona subtilis | a foliage spider | 2 | 2003 |
| spider | Clubiona terrestris | a foliage spider | 24 | 2013 |
| spider | Cnephalocotes obscurus | a money spider | 4 | 2019 |
| spider | Coelotes | a Coelotes species (unidentified) | 3 | 2023 |
| spider | Coelotes atropos | a cobweb spider | 25 | 2023 |
| spider | Coelotes terrestris | a cobweb spider | 2 | 1999 |
| spider | Collinsia inerrans | a money spider | 12 | 2003 |
| spider | Cozyptila blackwalli | a crab spider | 1 | 1968 |
| spider | Crustulina guttata | a comb-footed spider | 2 | 1988 |
| spider | Cyclosa conica | Trash-line Spider | 16 | 2020 |
| springtail | Ceratophysella armata | a springtail (Collembola) | 2 | 1925 |
| springtail | Collembola | Springtails | 33 | 2023 |
| springtail | Cyphoderus albinus | a springtail (Collembola) | 1 | 2015 |
| tick or mite (acarine) | Camisia | a Camisia species (unidentified) | 1 | 1983 |
| tick or mite (acarine) | Cecidophyes galii | a gall mite | 5 | 2012 |
| tick or mite (acarine) | Cecidophyes nudus | Galium Gall Mite | 2 | 2020 |
| tick or mite (acarine) | Cecidophyes rouhollahi | Galium Gall Mite | 2 | 2023 |
| tick or mite (acarine) | Cecidophyopsis ribis | a gall mite | 1 | 2002 |
| tick or mite (acarine) | Colomerus vitis | a gall mite | 1 | 2025 |
| true fly - | Calamoncosis aprica | a fly | 3 | 2009 |
| true fly - | Calamoncosis glyceriae | a fly | 3 | 1999 |
| true fly - | Calamoncosis minima | a fly | 1 | 1983 |
| true fly - | Calliopum | a Calliopum species (unidentified) | 1 | 2015 |
| true fly - | Calliopum aeneum | a fly | 1 | 1993 |
| true fly - | Calliopum elisae | a fly | 3 | 2009 |
| true fly - | Calliopum simillimum | a fly | 9 | 2021 |
| true fly - | Calliopum tuberculosum | a fly | 12 | 2020 |
| true fly - | Calliphora | Bluebottle | 11 | 2023 |
| true fly - | Calliphora vicina | Common Bluebottle | 35 | 2023 |
| true fly - | Calliphora vomitoria | Orange-bearded Bluebottle | 17 | 2023 |
| true fly - | Calliphoridae | a blue bottle or green bottle or cluster fly (unidentified) | 29 | 2023 |
| true fly - | Calliphorinae | a Calliphorinae species (unidentified) | 1 | 2023 |
| true fly - | Callomyia dives | a big-footed fly | 1 | 1900 |
| true fly - | Calycomyza humeralis | a leaf-mining fly | 1 | 2014 |
| true fly - | Calyptratae | a Calyptratae species (unidentified) | 3 | 2023 |
| true fly - | Camilla glabra | a fly | 2 | 2001 |
| true fly - | Campichoeta obscuripennis | a fly | 2 | 2009 |
| true fly - | Campichoeta punctum | a fly | 1 | 1999 |
| true fly - | Canace nasica | a fly | 1 | 1995 |
| true fly - | Carcelia lucorum | a parasitic fly | 2 | 2000 |
| true fly - | Cecidomyiidae | a Cecidomyiidae species (unidentified) | 4 | 2008 |
| true fly - | Ceratinostoma ostiorum | a dung fly | 1 | 2019 |
| true fly - | Cerodontha atra | a leaf-mining fly | 4 | 2006 |
| true fly - | Cerodontha bimaculata | a leaf-mining fly | 4 | 2006 |
| true fly - | Cerodontha biseta | a leaf-mining fly | 3 | 2008 |
| true fly - | Cerodontha capitata | a leaf-mining fly | 4 | 2002 |
| true fly - | Cerodontha denticornis | a leaf-mining fly | 16 | 2008 |
| true fly - | Cerodontha iraeos | a leaf-mining fly | 2 | 2020 |
| true fly - | Cerodontha lateralis | a leaf-mining fly | 3 | 2008 |
| true fly - | Cerodontha luctuosa | a leaf-mining fly | 3 | 2001 |
| true fly - | Ceroxys urticae | a fly | 3 | 2019 |
| true fly - | Cetema elongatum | a fly | 1 | 2002 |
| true fly - | Cetema neglectum | a fly | 16 | 2022 |
| true fly - | Cetema simile | a fly | 3 | 2004 |
| true fly - | Chalarus fimbriatus | a big-headed fly | 1 | 1999 |
| true fly - | Chalarus latifrons | a big-headed fly | 1 | 2000 |
| true fly - | Chalarus spurius | a big-headed fly | 3 | 2003 |
| true fly - | Chamaemyia aridella | a fly | 6 | 2013 |
| true fly - | Chamaemyia fasciata | a fly | 1 | 2001 |
| true fly - | Chamaemyia herbarum | a fly | 1 | 2008 |
| true fly - | Chamaemyia juncorum | a fly | 1 | 2023 |
| true fly - | Chamaemyia nigripalpis | a fly | 1 | 2000 |
| true fly - | Chamaemyia polystigma | a fly | 11 | 2006 |
| true fly - | Chamaepsila bicolor | a fly | 1 | 2006 |
| true fly - | Chamaepsila persimilis | a fly | 1 | 2008 |
| true fly - | Chaoborus | a Chaoborus species (unidentified) | 5 | 2007 |
| true fly - | Chironominae | a Chironominae species (unidentified) | 5 | 2023 |
| true fly - | Chironomini | a Chironomini species (unidentified) | 2 | 2023 |
| true fly - | Chirosia betuleti | a fly | 9 | 2003 |
| true fly - | Chirosia grossicauda | a fly | 8 | 2016 |
| true fly - | Chirosia histricina | a fly | 1 | 2011 |
| true fly - | Chloromyia | a Chloromyia species (unidentified) | 1 | 2019 |
| true fly - | Chloropidae | a Chloropidae species (unidentified) | 3 | 2020 |
| true fly - | Chlorops calceatus | a fly | 4 | 2002 |
| true fly - | Chlorops hypostigma | a fly | 6 | 2008 |
| true fly - | Chlorops interruptus | a fly | 1 | 2017 |
| true fly - | Chlorops laetus | a fly | 1 | 1950 |
| true fly - | Chlorops limbatus | a fly | 2 | 1983 |
| true fly - | Chlorops obscurellus | a fly | 2 | 1983 |
| true fly - | Chlorops pumilionis | a fly | 14 | 2023 |
| true fly - | Chlorops rufinus | a fly | 5 | 2006 |
| true fly - | Chlorops scalaris | a fly | 3 | 2006 |
| true fly - | Chlorops serenus | a fly | 3 | 2008 |
| true fly - | Chlorops speciosus | a fly | 5 | 2004 |
| true fly - | Choerades marginatus | Golden-haired Robberfly | 2 | 2001 |
| true fly - | Chonocephalus | a Chonocephalus species (unidentified) | 2 | 1997 |
| true fly - | Chromatomyia | a Chromatomyia species (unidentified) | 4 | 2013 |
| true fly - | Chromatomyia aprilina | a leaf-mining fly | 1 | 2020 |
| true fly - | Chromatomyia centaurii | a leaf-mining fly | 1 | 2006 |
| true fly - | Chromatomyia horticola | a leaf-mining fly | 3 | 2014 |
| true fly - | Chromatomyia lonicerae | a leaf-mining fly | 2 | 2014 |
| true fly - | Chromatomyia milii | a leaf-mining fly | 10 | 2020 |
| true fly - | Chromatomyia nigra | a leaf-mining fly | 23 | 2020 |
| true fly - | Chromatomyia periclymeni | a leaf-mining fly | 1 | 2020 |
| true fly - | Chromatomyia primulae | a leaf-mining fly | 6 | 2021 |
| true fly - | Chromatomyia ramosa | a leaf-mining fly | 3 | 2020 |
| true fly - | Chromatomyia scolopendri | a leaf-mining fly | 13 | 2023 |
| true fly - | Chromatomyia syngenesiae | a leaf-mining fly | 5 | 2017 |
| true fly - | Chrysotoxum | a Chrysotoxum species (unidentified) | 5 | 2021 |
| true fly - | Chrysotus | a Chrysotus species (unidentified) | 1 | 2011 |
| true fly - | Chyliza extenuata | a fly | 3 | 2022 |
| true fly - | Chyliza leptogaster | a fly | 3 | 2004 |
| true fly - | Chyromyidae | a Chyromyidae species (unidentified) | 1 | 2016 |
| true fly - | Cinochira atra | a parasitic fly | 1 | 2004 |
| true fly - | Cistogaster globosa | a parasitic fly | 3 | 2020 |
| true fly - | Cleigastra apicalis | a dung fly | 2 | 2004 |
| true fly - | Clinohelea | a Clinohelea species (unidentified) | 2 | 1983 |
| true fly - | Clusia flava | a fly | 6 | 2001 |
| true fly - | Clusia tigrina | a fly | 12 | 2023 |
| true fly - | Clusiodes albimanus | a fly | 12 | 2009 |
| true fly - | Clusiodes gentilis | a fly | 3 | 2022 |
| true fly - | Clusiodes verticalis | a fly | 3 | 2000 |
| true fly - | Clytocerus ocellaris | a moth fly | 5 | 2020 |
| true fly - | Coboldia fuscipes | a fly | 1 | 1996 |
| true fly - | Coelopa frigida | a wrack fly | 2 | 2002 |
| true fly - | Coenia curvicauda | a shore fly | 1 | 2009 |
| true fly - | Coenia palustris | a shore fly | 1 | 2009 |
| true fly - | Coenosia agromyzina | a muscid fly | 5 | 2009 |
| true fly - | Coenosia albicornis | a muscid fly | 2 | 2001 |
| true fly - | Coenosia atra | a muscid fly | 2 | 2002 |
| true fly - | Coenosia femoralis | a muscid fly | 2 | 2013 |
| true fly - | Coenosia humilis | a muscid fly | 1 | 1998 |
| true fly - | Coenosia infantula | a muscid fly | 18 | 2008 |
| true fly - | Coenosia mollicula | a muscid fly | 8 | 2009 |
| true fly - | Coenosia pedella | a muscid fly | 2 | 2013 |
| true fly - | Coenosia pumila | a muscid fly | 5 | 2013 |
| true fly - | Coenosia testacea | a muscid fly | 15 | 2022 |
| true fly - | Coenosia tigrina | a muscid fly | 15 | 2023 |
| true fly - | Conicera dauci | a scuttle fly | 3 | 2008 |
| true fly - | Conioscinella frontella | a fly | 3 | 2004 |
| true fly - | Conioscinella gallarum | a fly | 1 | 2006 |
| true fly - | Coproica ferruginata | a lesser dung fly | 2 | 2025 |
| true fly - | Coproica pusio | a lesser dung fly | 1 | 2003 |
| true fly - | Copromyza equina | a lesser dung fly | 2 | 2022 |
| true fly - | Copromyza nigrina | a lesser dung fly | 1 | 1994 |
| true fly - | Cordilura albipes | a dung fly | 10 | 2021 |
| true fly - | Cordilura ciliata | a dung fly | 1 | 1999 |
| true fly - | Cordilura pubera | a dung fly | 5 | 2022 |
| true fly - | Cordilura pudica | a dung fly | 1 | 2006 |
| true fly - | Coremacera | a Coremacera species (unidentified) | 1 | 2014 |
| true fly - | Coremacera marginata | a snail-killing fly | 34 | 2024 |
| true fly - | Corynoneura | a Corynoneura species (unidentified) | 1 | 1983 |
| true fly - | Corynoptera flavicauda | a fly | 1 | 2001 |
| true fly - | Corynoptera forcipata | a fly | 2 | 2021 |
| true fly - | Crumomyia fimetaria | a lesser dung fly | 2 | 2020 |
| true fly - | Crumomyia nitida | a lesser dung fly | 4 | 2020 |
| true fly - | Crumomyia pedestris | a lesser dung fly | 2 | 2023 |
| true fly - | Crumomyia roserii | a lesser dung fly | 3 | 2020 |
| true fly - | Cryptonevra diadema | a fly | 1 | 2009 |
| true fly - | Cryptonevra flavitarsis | a fly | 10 | 2009 |
| true fly - | Culicoides | a Culicoides species (unidentified) | 3 | 2014 |
| true fly - | Culicomorpha | a Culicomorpha species (unidentified) | 1 | 2023 |
| true fly - | Cyclorrhapha | a Cyclorrhapha species (unidentified) | 2 | 2023 |
| true fly - | Cynomya mortuorum | Yellow-faced Blowfly | 5 | 1997 |
| true fly - | Cyzenis albicans | a parasitic fly | 1 | 2019 |
| true fly - cranefly | Cheilotrichia cinerascens | a cranefly | 10 | 2022 |
| true fly - cranefly | Crypteria limnophiloides | a cranefly | 2 | 2003 |
| true fly - cranefly | Ctenophora pectinicornis | a cranefly | 7 | 2022 |
| true fly - (diptera) | Campiglossa malaris | an insect - true fly (Diptera) | 5 | 2009 |
| true fly - (diptera) | Campiglossa plantaginis | an insect - true fly (Diptera) | 11 | 2019 |
| true fly - (diptera) | Cerodontha iridis | an insect - true fly (Diptera) | 1 | 2015 |
| true fly - (diptera) | Cerodontha morosa | an insect - true fly (Diptera) | 3 | 2006 |
| true fly - (diptera) | Cerodontha spinata | an insect - true fly (Diptera) | 1 | 2001 |
| true fly - (diptera) | Chamaepsila rosae preocc. | an insect - true fly (Diptera) | 7 | 2001 |
| true fly - (diptera) | Chironomus alpestris | an insect - true fly (Diptera) | 1 | 1983 |
| true fly - (diptera) | Coquillettidia richiardii | an insect - true fly (Diptera) | 7 | 2012 |
| true fly - (diptera) | Corynoptera inundata | an insect - true fly (Diptera) | 1 | 2003 |
| true fly - (diptera) | Crataerina hirundinis | an insect - true fly (Diptera) | 1 | 1969 |
| true fly - (diptera) | Cratyna vagabunda | an insect - true fly (Diptera) | 1 | 2006 |
| true fly - (diptera) | Crossopalpus nigritellus | an insect - true fly (Diptera) | 1 | 1983 |
| true fly - fly | Colobaea bifasciella | a snail-killing fly | 1 | 2009 |
| true fly - fly | Colobaea distincta | a snail-killing fly | 1 | 2009 |
| true fly - fly | Colobaea pectoralis | a snail-killing fly | 1 | 1984 |
| true fly - fly | Colobaea punctata | a snail-killing fly | 2 | 2004 |
| true fly - horse fly | Chrysops | a Chrysops horse fly (unidentified) | 1 | 2021 |
| true fly - horse fly | Chrysops caecutiens | Splayed Deerfly | 29 | 2023 |
| true fly - horse fly | Chrysops relictus | Twin-lobed Deerfly | 14 | 2021 |
| true fly - horse fly | Chrysops viduatus | Square-spot Deerfly | 10 | 2021 |
| true fly - hoverfly | Chalcosyrphus nemorum | a hoverfly | 8 | 2023 |
| true fly - hoverfly | Cheilosia | a Cheilosia hoverfly (unidentified) | 14 | 2023 |
| true fly - hoverfly | Cheilosia albipila | a hoverfly | 2 | 2000 |
| true fly - hoverfly | Cheilosia albitarsis | a hoverfly | 79 | 2023 |
| true fly - hoverfly | Cheilosia albitarsis sens.lat. | a hoverfly | 5 | 2018 |
| true fly - hoverfly | Cheilosia antiqua | a hoverfly | 5 | 2023 |
| true fly - hoverfly | Cheilosia barbata | a hoverfly | 3 | 1999 |
| true fly - hoverfly | Cheilosia bergenstammi | a hoverfly | 27 | 2020 |
| true fly - hoverfly | Cheilosia cynocephala | a hoverfly | 1 | 1970 |
| true fly - hoverfly | Cheilosia fraterna | a hoverfly | 11 | 2016 |
| true fly - hoverfly | Cheilosia griseiventris | a hoverfly | 1 | 2003 |
| true fly - hoverfly | Cheilosia grossa | a hoverfly | 13 | 2000 |
| true fly - hoverfly | Cheilosia illustrata | a hoverfly | 154 | 2024 |
| true fly - hoverfly | Cheilosia impressa | a hoverfly | 37 | 2020 |
| true fly - hoverfly | Cheilosia lasiopa | a hoverfly | 4 | 2011 |
| true fly - hoverfly | Cheilosia latifrons | a hoverfly | 9 | 2009 |
| true fly - hoverfly | Cheilosia longula | a hoverfly | 3 | 2023 |
| true fly - hoverfly | Cheilosia mutabilis | a hoverfly | 1 | 1950 |
| true fly - hoverfly | Cheilosia pagana | a hoverfly | 99 | 2023 |
| true fly - hoverfly | Cheilosia proxima | a hoverfly | 39 | 2023 |
| true fly - hoverfly | Cheilosia psilophthalma | a hoverfly | 1 | 2003 |
| true fly - hoverfly | Cheilosia ranunculi | a hoverfly | 11 | 2023 |
| true fly - hoverfly | Cheilosia scutellata | a hoverfly | 15 | 2023 |
| true fly - hoverfly | Cheilosia soror | a hoverfly | 37 | 2023 |
| true fly - hoverfly | Cheilosia urbana | a hoverfly | 3 | 2003 |
| true fly - hoverfly | Cheilosia variabilis | a hoverfly | 24 | 2022 |
| true fly - hoverfly | Cheilosia vernalis | a hoverfly | 28 | 2022 |
| true fly - hoverfly | Cheilosia vulpina | a hoverfly | 15 | 2023 |
| true fly - hoverfly | Chrysogaster | a Chrysogaster hoverfly (unidentified) | 3 | 2016 |
| true fly - hoverfly | Chrysogaster cemiteriorum | a hoverfly | 3 | 2022 |
| true fly - hoverfly | Chrysogaster solstitialis | a hoverfly | 31 | 2023 |
| true fly - hoverfly | Chrysotoxum bicinctum | a hoverfly | 190 | 2025 |
| true fly - hoverfly | Chrysotoxum cautum | a hoverfly | 58 | 2023 |
| true fly - hoverfly | Chrysotoxum elegans | Zipperback | 15 | 2006 |
| true fly - hoverfly | Chrysotoxum festivum | a hoverfly | 32 | 2023 |
| true fly - hoverfly | Criorhina asilica | a hoverfly | 2 | 2008 |
| true fly - hoverfly | Criorhina berberina | a hoverfly | 15 | 2020 |
| true fly - hoverfly | Criorhina floccosa | a hoverfly | 12 | 2025 |
| true fly - hoverfly | Criorhina ranunculi | a hoverfly | 14 | 2015 |
| true fly - midge, gnat or mosquito | Camptocladius stercorarius | a non-biting midge | 1 | 1997 |
| true fly - midge, gnat or mosquito | Ceratopogonidae | Mosquitos or gnats | 37 | 2023 |
| true fly - midge, gnat or mosquito | Cerotelion striatum | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Chaoboridae | Phantom or ghost midges | 37 | 2020 |
| true fly - midge, gnat or mosquito | Chaoboridae sp. or Dixidae sp. or Chaobridae sp. or Ceratopogonidae sp. or Thaumaleidae sp. or Cecidomyiidae sp. | a midge (unidentified) | 15 | 2011 |
| true fly - midge, gnat or mosquito | Chaoborus crystallinus | a phantom midge | 4 | 2009 |
| true fly - midge, gnat or mosquito | Chaoborus flavicans | a phantom midge | 1 | 1997 |
| true fly - midge, gnat or mosquito | Chaoborus pallidus | a phantom midge | 2 | 1997 |
| true fly - midge, gnat or mosquito | Chironomidae | Non-biting midges | 182 | 2023 |
| true fly - midge, gnat or mosquito | Chironomus | a Chironomus non-biting midge (unidentified) | 2 | 2010 |
| true fly - midge, gnat or mosquito | Chironomus cingulatus | a non-biting midge | 2 | 1996 |
| true fly - midge, gnat or mosquito | Chironomus longistylus | a non-biting midge | 2 | 2003 |
| true fly - midge, gnat or mosquito | Chironomus luridus | a non-biting midge | 4 | 2020 |
| true fly - midge, gnat or mosquito | Chironomus plumosus | a non-biting midge | 2 | 2019 |
| true fly - midge, gnat or mosquito | Chironomus pseudothummi | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Chironomus riparius | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Clinotanypus nervosus | a non-biting midge | 1 | 2025 |
| true fly - midge, gnat or mosquito | Coelophthinia thoracica | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Coelosia flava | a fungus gnat | 1 | 2004 |
| true fly - midge, gnat or mosquito | Contarinia coryli | a gall midge | 1 | 2020 |
| true fly - midge, gnat or mosquito | Contarinia jacobaeae | a gall midge | 3 | 2000 |
| true fly - midge, gnat or mosquito | Contarinia tiliarum | a gall midge | 2 | 1997 |
| true fly - midge, gnat or mosquito | Cordyla brevicornis | a fungus gnat | 1 | 2020 |
| true fly - midge, gnat or mosquito | Cordyla crassicornis | a fungus gnat | 5 | 2003 |
| true fly - midge, gnat or mosquito | Cordyla fissa | a fungus gnat | 2 | 2001 |
| true fly - midge, gnat or mosquito | Cordyla murina | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Craneiobia corni | a gall midge | 1 | 2011 |
| true fly - midge, gnat or mosquito | Cricotopus | a Cricotopus non-biting midge (unidentified) | 3 | 2023 |
| true fly - midge, gnat or mosquito | Cricotopus sylvestris | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Culex | a Culex mosquito (unidentified) | 4 | 2023 |
| true fly - midge, gnat or mosquito | Culex pipiens | a mosquito | 32 | 2023 |
| true fly - midge, gnat or mosquito | Culex territans | a mosquito | 2 | 2007 |
| true fly - midge, gnat or mosquito | Culicidae | Mosquito | 87 | 2023 |
| true fly - midge, gnat or mosquito | Culicoides achrayi | a biting midge | 1 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides dewulfi | a biting midge | 1 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides obsoletus | a biting midge | 2 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides pulicaris | a biting midge | 3 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides punctatus | a biting midge | 1 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides scoticus | a biting midge | 1 | 2009 |
| true fly - midge, gnat or mosquito | Culicoides vexans | a biting midge | 3 | 1997 |
| true fly - midge, gnat or mosquito | Culiseta | a Culiseta mosquito (unidentified) | 28 | 2013 |
| true fly - midge, gnat or mosquito | Culiseta annulata | a mosquito | 22 | 2022 |
| true fly - midge, gnat or mosquito | Culiseta fumipennis | a mosquito | 1 | 1978 |
| true fly - midge, gnat or mosquito | Culiseta morsitans | a mosquito | 1 | 1999 |
| true fly - picture-winged, conopid or stilt-legged fly | Campiglossa absinthii | a gall fly | 2 | 2004 |
| true fly - picture-winged, conopid or stilt-legged fly | Chaetorellia jaceae | a gall fly | 1 | 2021 |
| true fly - picture-winged, conopid or stilt-legged fly | Chaetostomella cylindrica | a gall fly | 20 | 2019 |
| true fly - picture-winged, conopid or stilt-legged fly | Chetostoma curvinerve | a gall fly | 4 | 2018 |
| true fly - picture-winged, conopid or stilt-legged fly | Conops flavipes | a fly | 4 | 2022 |
| true fly - picture-winged, conopid or stilt-legged fly | Conops quadrifasciatus | a fly | 37 | 2020 |
| true fly - picture-winged, conopid or stilt-legged fly | Conops strigatus | a fly | 1 | 1973 |
| true fly - robber, empid or dolichopid fly | Campsicnemus curvipes | a dolichopodid fly | 37 | 2023 |
| true fly - robber, empid or dolichopid fly | Campsicnemus loripes | a dolichopodid fly | 2 | 2002 |
| true fly - robber, empid or dolichopid fly | Campsicnemus scambus | a dolichopodid fly | 5 | 2023 |
| true fly - robber, empid or dolichopid fly | Chelifera precatoria | a dance fly | 3 | 2001 |
| true fly - robber, empid or dolichopid fly | Chrysotimus flaviventris | a dolichopodid fly | 8 | 2020 |
| true fly - robber, empid or dolichopid fly | Chrysotimus molliculus | a dolichopodid fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Chrysotus blepharosceles | a dolichopodid fly | 14 | 2022 |
| true fly - robber, empid or dolichopid fly | Chrysotus cilipes | a dolichopodid fly | 6 | 1983 |
| true fly - robber, empid or dolichopid fly | Chrysotus cupreus | a dolichopodid fly | 4 | 2021 |
| true fly - robber, empid or dolichopid fly | Chrysotus femoratus | a dolichopodid fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Chrysotus gramineus | a dolichopodid fly | 56 | 2022 |
| true fly - robber, empid or dolichopid fly | Chrysotus neglectus | a dolichopodid fly | 3 | 2023 |
| true fly - robber, empid or dolichopid fly | Clinocera stagnalis | a dance fly | 2 | 2000 |
| true fly - soldier or snipe fly | Chloromyia formosa | Broad Centurion | 351 | 2024 |
| true fly - soldier or snipe fly | Chorisops nagatomii | Bright Four-spined Legionnaire | 11 | 2021 |
| true fly - soldier or snipe fly | Chorisops tibialis | Dull Four-spined Legionnaire | 26 | 2023 |
| true fly - soldier or snipe fly | Chrysopilus asiliformis | Little Snipefly | 23 | 2022 |
| true fly - soldier or snipe fly | Chrysopilus cristatus | Black Snipefly | 80 | 2024 |
| true fly - soldier or snipe fly | Chrysopilus laetus | Tree Snipefly | 1 | 2021 |
| two-tailed bristletail | Campodea | a Campodea species (unidentified) | 8 | 2023 |
| two-tailed bristletail | Campodea staphylinus | a two-pronged bristle tail | 3 | 1997 |
| two-tailed bristletail | Campodeidae | a Campodeidae species (unidentified) | 1 | 2023 |
| water flea | Chydorus sphaericus | a water flea | 1 | 1995 |
| water flea | Cladocera | a water flea (unidentified) | 89 | 2016 |
| water flea | Copepoda | Cyclopid Water-Flea | 20 | 2007 |
| woodlouse | Cyathura carinata | a woodlouse or sea slater | 4 | 1976 |