Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| alder fly, lacewing or snake fly | Sialidae | a Sialidae species (unidentified) | 5 | 2018 |
| alder fly, lacewing or snake fly | Sialis | an alder fly (unidentified) | 21 | 2023 |
| alder fly, lacewing or snake fly | Sialis fuliginosa | an Alder Fly | 1 | 1997 |
| alder fly, lacewing or snake fly | Sialis lutaria | an Alder Fly | 55 | 2023 |
| alder fly, lacewing or snake fly | Sympherobius (Niremberge) pellucidus | a brown lacewing | 1 | 2012 |
| algae or stonewort | Seaweed | a Seaweed species (unidentified) | 7 | 2019 |
| algae or stonewort | Solieria | a Solieria species (unidentified) | 1 | 2019 |
| algae or stonewort | Spirogyra | a Spirogyra green algae (unidentified) | 1 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sapyga quinquepunctata | a solitary wasp | 4 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Scambus brevicornis | an ichneumon wasp | 2 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Scambus elegans | an ichneumon wasp | 3 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Scambus inanis | an ichneumon wasp | 3 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Scambus signatus | an insect - hymenopteran | 2 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Scelio walkeri | a parasitic wasp | 5 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Schizopyga frigida | an ichneumon wasp | 5 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Seladerma tarsale | a chalcid wasp | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Selandria serva | a sawfly | 5 | 2022 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sirex juvencus | a woodwasp | 1 | 1987 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sirex noctilio | Lesser Horntail Wasp | 3 | 1996 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Spalangia cameroni | a chalcid wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecidae | a Sphecidae wasp (unidentified) | 2 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes | a Sphecodes species (unidentified) | 10 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes crassus | a solitary bee | 4 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes ephippius | a solitary bee | 12 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes ferruginatus | a solitary bee | 4 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes geoffrellus | a solitary bee | 5 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes gibbus | a solitary bee | 5 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes hyalinatus | a solitary bee | 13 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes monilicornis | a solitary bee | 15 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes niger | a solitary bee | 3 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes puncticeps | a solitary bee | 1 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes reticulatus | a solitary bee | 5 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphecodes rubicundus | a solitary bee | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sphegigaster pallicornis | a chalcid wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Spilomena curruca | a solitary wasp | 1 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stauropoctonus bombycivorus | an ichneumon wasp | 1 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stelis ornatula | a solitary bee | 5 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stenamma debile | an insect - hymenopteran | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stenodontus marginellus | an ichneumon wasp | 1 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stenomacrus laricis | an insect - hymenopteran | 2 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stethomostus fuliginosus | a sawfly | 1 | 1983 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stigmus solskyi | a solitary wasp | 3 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stilbops vetula | an ichneumon wasp | 2 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stilpnus gagates | an insect - hymenopteran | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Stromboceros delicatulus | a sawfly | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Strongylogaster multifasciata | a sawfly | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sussaba cognata | an ichneumon wasp | 3 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sussaba dorsalis | an ichneumon wasp | 1 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sussaba pulchella | an ichneumon wasp | 8 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sycophila biguttata | a chalcid wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Sycophila variegata | a chalcid wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Symmorphus | a Symmorphus species (unidentified) | 1 | 2010 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Symmorphus bifasciatus | a potter wasp or mason wasp | 8 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Symmorphus gracilis | a potter wasp or mason wasp | 5 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Symphyta | a sawfly or a horntail or a wood wasp (unidentified) | 8 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus albipes | a gall wasp | 3 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus apicalis | a gall wasp | 1 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus gallaepomiformis | a gall wasp | 46 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus incrassatus | a gall wasp | 1 | 1996 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus nervosus | a gall wasp | 8 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus pallicornis | a gall wasp | 2 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus pallidipennis | a gall wasp | 5 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus reinhardi | a gall wasp | 64 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synergus umbraculus | a gall wasp | 26 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Synopeas sp. | a Synopeas species (unidentified) | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Syrphoctonus fissorius | an ichneumon wasp | 1 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Syrphoctonus tarsatorius | an ichneumon wasp | 4 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Syrphophilus tricinctorius | an ichneumon wasp | 3 | 2008 |
| beetle | Salpingus planirostris | a false weevil | 19 | 2020 |
| beetle | Salpingus ruficollis | a false weevil | 6 | 2020 |
| beetle | Saprinus planiusculus | a carrion beetle | 2 | 1996 |
| beetle | Saprinus semistriatus | a carrion beetle | 4 | 2003 |
| beetle | Scaphidema metallicum | a darkling beetle | 2 | 1997 |
| beetle | Scaphidium quadrimaculatum | a shining fungus beetle | 15 | 2019 |
| beetle | Scaphisoma agaricinum | a shining fungus beetle | 2 | 2015 |
| beetle | Scaphisoma boleti | a shining fungus beetle | 1 | 2016 |
| beetle | Scarabaeidae | a Scarabaeidae species (unidentified) | 6 | 2023 |
| beetle | Sciaphilus asperatus | a Strawberry Root Weevil | 11 | 2022 |
| beetle | Sciodrepoides fumatus | a round fungus beetle | 12 | 2017 |
| beetle | Sciodrepoides watsoni | a round fungus beetle | 12 | 2020 |
| beetle | Scirtes | a Scirtes species (unidentified) | 1 | 1983 |
| beetle | Scirtes hemisphaericus | a marsh beetle | 27 | 2002 |
| beetle | Scirtes orbicularis | a marsh beetle | 7 | 1999 |
| beetle | Scirtidae | a Scirtidae species (unidentified) | 65 | 2018 |
| beetle | Scolytus | a Scolytus species (unidentified) | 1 | 2013 |
| beetle | Scolytus intricatus | a bark or ambrosia beetle | 6 | 2017 |
| beetle | Scolytus mali | Large Fruit Bark Beetle | 7 | 2020 |
| beetle | Scolytus rugulosus | Fruit Bark Beetle | 8 | 2017 |
| beetle | Scolytus scolytus | Large Elm Bark Beetle | 12 | 2016 |
| beetle | Scopaeus sulcicollis | a rove beetle | 1 | 2008 |
| beetle | Scraptia testacea | a tumbling flower beetle | 1 | 2016 |
| beetle | Scydmaenus tarsatus | a small antlike beetle | 3 | 2021 |
| beetle | Scydmoraphes helvolus | a small antlike beetle | 1 | 2016 |
| beetle | Scymnus auritus | a ladybird | 2 | 2019 |
| beetle | Scymnus frontalis | a ladybird | 6 | 2019 |
| beetle | Scymnus haemorrhoidalis | a ladybird | 3 | 2019 |
| beetle | Sepedophilus bipunctatus | a rove beetle | 1 | 2001 |
| beetle | Sepedophilus littoreus | a rove beetle | 2 | 2018 |
| beetle | Sepedophilus marshami | a rove beetle | 3 | 2015 |
| beetle | Sepedophilus testaceus | a rove beetle | 4 | 2001 |
| beetle | Serica brunnea | Brown Chafer | 18 | 2021 |
| beetle | Sericoderus | a Sericoderus minute fungus beetle (unidentified) | 20 | 2021 |
| beetle | Sericoderus brevicornis | a minute fungus beetle | 10 | 2021 |
| beetle | Sericoderus lateralis | a minute fungus beetle | 12 | 2019 |
| beetle | Sermylassa halensis | a leaf beetle | 20 | 2019 |
| beetle | Siagonium quadricorne | a rove beetle | 15 | 2020 |
| beetle | Silpha atrata | Black Snail Beetle | 41 | 2023 |
| beetle | Silpha atrata subsp. atrata | a Beetle | 1 | 2021 |
| beetle | Silpha laevigata | a sexton beetle | 3 | 2013 |
| beetle | Silpha obscura | a sexton beetle | 2 | 2010 |
| beetle | Silpha tristis | a sexton beetle | 15 | 2023 |
| beetle | Silphidae | a Silphidae species (unidentified) | 1 | 2018 |
| beetle | Simplocaria semistriata | a pill beetle | 5 | 2011 |
| beetle | Sinodendron cylindricum | Rhinoceros Beetle | 32 | 2023 |
| beetle | Sitona | a Sitona species (unidentified) | 5 | 2023 |
| beetle | Sitona ambiguus | a weevil | 17 | 2010 |
| beetle | Sitona cylindricollis | a weevil | 1 | 2018 |
| beetle | Sitona hispidulus | Clover-root Weevil | 34 | 2020 |
| beetle | Sitona humeralis | a weevil | 8 | 2019 |
| beetle | Sitona lepidus | a weevil | 31 | 2021 |
| beetle | Sitona lineatus | Pea and Bean Weevil | 98 | 2023 |
| beetle | Sitona puncticollis | a weevil | 10 | 2019 |
| beetle | Sitona striatellus | a weevil | 7 | 2016 |
| beetle | Sitona sulcifrons | a Clover Weevil | 10 | 2020 |
| beetle | Sitona suturalis | a weevil | 45 | 2018 |
| beetle | Sitona waterhousei | a weevil | 4 | 2018 |
| beetle | Soronia | a Soronia species (unidentified) | 1 | 2023 |
| beetle | Soronia grisea | a pollen or sap beetle | 17 | 2022 |
| beetle | Soronia punctatissima | a pollen or sap beetle | 5 | 2020 |
| beetle | Sphaeridium bipustulatum | a scavenger water beetle | 5 | 2022 |
| beetle | Sphaeridium lunatum | a scavenger water beetle | 4 | 2019 |
| beetle | Sphaeridium scarabaeoides | a scavenger water beetle | 21 | 2022 |
| beetle | Sphaeriestes reyi | a false weevil | 1 | 1998 |
| beetle | Sphaeroderma rubidum | a leaf beetle | 6 | 2017 |
| beetle | Sphaeroderma testaceum | a leaf beetle | 14 | 2022 |
| beetle | Sphaerosoma quercus | a false ladybird | 1 | 2001 |
| beetle | Sphindus dubius | a slime mould beetle | 1 | 2001 |
| beetle | Sphinginus lobatus | a malachite beetle | 1 | 2022 |
| beetle | Squamapion atomarium | a seed weevil | 2 | 1968 |
| beetle | Squamapion flavimanum | a seed weevil | 8 | 2010 |
| beetle | Staphylinidae | a rove beetle (unidentified) | 22 | 2023 |
| beetle | Staphylinini | a Staphylinini species (unidentified) | 1 | 2023 |
| beetle | Staphylinus | a Staphylinus species (unidentified) | 1 | 2008 |
| beetle | Staphylinus caesareus | a rove beetle | 2 | 2002 |
| beetle | Staphylinus dimidiaticornis | a rove beetle | 7 | 2021 |
| beetle | Staphylinus erythropterus | a rove beetle | 4 | 2021 |
| beetle | Stegobium paniceum | Biscuit Beetle | 4 | 2017 |
| beetle | Stenagostus rhombeus | a click beetle | 8 | 2020 |
| beetle | Stenelmis canaliculata | a riffle beetle | 1 | 1996 |
| beetle | Stenichnus collaris | a small antlike beetle | 2 | 2020 |
| beetle | Stenocarus ruficornis | a weevil | 1 | 1978 |
| beetle | Stenocorus meridianus | a longhorn beetle | 23 | 2022 |
| beetle | Stenolophus mixtus | a ground beetle | 7 | 2020 |
| beetle | Stenolophus skrimshiranus | a ground beetle | 2 | 1986 |
| beetle | Stenopelmus rufinasus | Azolla Weevil | 23 | 2004 |
| beetle | Stenopterapion meliloti | a seed weevil | 3 | 2001 |
| beetle | Stenostola dubia | a longhorn beetle | 4 | 2007 |
| beetle | Stenurella melanura | a longhorn beetle | 19 | 2022 |
| beetle | Stenurella nigra | a longhorn beetle | 1 | 2016 |
| beetle | Stenus | a Stenus species (unidentified) | 9 | 2023 |
| beetle | Stenus aceris | a rove beetle | 6 | 2021 |
| beetle | Stenus bifoveolatus | a rove beetle | 2 | 2002 |
| beetle | Stenus bimaculatus | a rove beetle | 8 | 2020 |
| beetle | Stenus binotatus | a rove beetle | 6 | 2021 |
| beetle | Stenus brunnipes | a rove beetle | 15 | 2022 |
| beetle | Stenus canescens | a rove beetle | 3 | 2004 |
| beetle | Stenus cicindeloides | a rove beetle | 18 | 2022 |
| beetle | Stenus clavicornis | a rove beetle | 59 | 2021 |
| beetle | Stenus flavipes | a rove beetle | 12 | 2021 |
| beetle | Stenus fulvicornis | a rove beetle | 27 | 2021 |
| beetle | Stenus geniculatus | a rove beetle | 1 | 2015 |
| beetle | Stenus impressus | a rove beetle | 44 | 2022 |
| beetle | Stenus juno | a rove beetle | 5 | 2015 |
| beetle | Stenus latifrons | a rove beetle | 12 | 2019 |
| beetle | Stenus nanus | a rove beetle | 5 | 2022 |
| beetle | Stenus nitidiusculus | a rove beetle | 11 | 2022 |
| beetle | Stenus ossium | a rove beetle | 21 | 2021 |
| beetle | Stenus pallipes | a rove beetle | 1 | 2015 |
| beetle | Stenus pallitarsis | a rove beetle | 2 | 1983 |
| beetle | Stenus picipennis | a rove beetle | 2 | 2009 |
| beetle | Stenus picipes | a rove beetle | 16 | 2022 |
| beetle | Stenus providus | a rove beetle | 3 | 2021 |
| beetle | Stenus pusillus | a rove beetle | 1 | 2015 |
| beetle | Stenus similis | a rove beetle | 2 | 2017 |
| beetle | Stenus solutus | a rove beetle | 3 | 2004 |
| beetle | Stenus subaeneus | a rove beetle | 1 | 2016 |
| beetle | Stenus tarsalis | a rove beetle | 4 | 2022 |
| beetle | Stephostethus alternans | a mould beetle | 1 | 2020 |
| beetle | Stephostethus lardarius | a mould beetle | 1 | 1992 |
| beetle | Stethorus punctillum | a ladybird | 1 | 2022 |
| beetle | Stictoleptura rubra | a longhorn beetle | 2 | 2011 |
| beetle | Stictotarsus duodecimpustulatus | a water beetle | 5 | 2000 |
| beetle | Stilbus testaceus | a smut beetle | 10 | 2019 |
| beetle | Stomis pumicatus | a ground beetle | 9 | 2015 |
| beetle | Stricticollis tobias | an antlike beetle | 1 | 2015 |
| beetle | Strigocis bicornis | a small fungus beetle | 2 | 2020 |
| beetle | Strophosoma melanogrammum | Nut Leaf Weevil | 10 | 2021 |
| beetle | Subcoccinella vigintiquattuorpunctata | 24-spot Ladybird | 193 | 2023 |
| beetle | Sunius bicolor | a rove beetle | 1 | 2019 |
| beetle | Sunius propinquus | a rove beetle | 16 | 2022 |
| beetle | Suphrodytes dorsalis (s. lat.) | a water beetle | 26 | 2012 |
| beetle | Suphrodytes figuratus | a water beetle | 1 | 2013 |
| beetle | Symbiotes latus | a false ladybird | 3 | 2021 |
| beetle | Syntomus foveatus | a ground beetle | 10 | 2021 |
| beetle | Syntomus obscuroguttatus | a ground beetle | 8 | 2019 |
| beetle | Syntomus truncatellus | a ground beetle | 2 | 2021 |
| beetle | Synuchus vivalis | a ground beetle | 15 | 2020 |
| bird | Saxicola rubetra | Whinchat | 3257 | 2022 |
| bird | Saxicola rubicola | Stonechat | 10348 | 2024 |
| bird | Scolopacidae | a wader (unidentified) | 4 | 2021 |
| bird | Scolopax rusticola | Woodcock | 726 | 2023 |
| bird | Serinus canaria | Canary | 2 | 2018 |
| bird | Serinus serinus | Serin | 4 | 2017 |
| bird | Sitta europaea | Nuthatch | 11430 | 2024 |
| bird | Somateria mollissima | Eider | 149 | 2022 |
| bird | Spatula clypeata | Shoveler | 9166 | 2024 |
| bird | Spatula cyanoptera | Cinnamon Teal | 3 | 1994 |
| bird | Spatula discors | Blue-winged Teal | 14 | 2003 |
| bird | Spatula querquedula | Garganey | 2446 | 2022 |
| bird | Spinus spinus | Siskin | 6982 | 2024 |
| bird | Stercorarius | a skua (unidentified) | 29 | 2022 |
| bird | Stercorarius longicaudus | Long-tailed Skua | 10 | 2021 |
| bird | Stercorarius parasiticus | Arctic Skua | 375 | 2022 |
| bird | Stercorarius pomarinus | Pomarine Skua | 128 | 2021 |
| bird | Stercorarius skua | Great Skua | 255 | 2022 |
| bird | Sterna | a tern (unidentified) | 31 | 2019 |
| bird | Sterna dougallii | Roseate Tern | 13 | 2019 |
| bird | Sterna hirundo | Common Tern | 1601 | 2022 |
| bird | Sterna hirundo or Sterna paradisaea | Common Tern or Arctic Tern | 25 | 2014 |
| bird | Sterna paradisaea | Arctic Tern | 868 | 2022 |
| bird | Sterna paradisaea/hirundo | Commic Tern | 96 | 2021 |
| bird | Sternula albifrons | Little Tern | 224 | 2022 |
| bird | Streptopelia | a Streptopelia species (unidentified) | 1 | 2016 |
| bird | Streptopelia decaocto | Collared Dove | 39236 | 2024 |
| bird | Streptopelia turtur | Turtle Dove | 874 | 2022 |
| bird | Strigidae sp. or Tytonidae sp (unidentified owl) | an owl (unidentified) | 40 | 2019 |
| bird | Strigiformes | a Strigiformes species (unidentified) | 3 | 2023 |
| bird | Strix aluco | Tawny Owl | 8036 | 2024 |
| bird | Sturnidae | a Sturnidae species (unidentified) | 10 | 2023 |
| bird | Sturnus vulgaris | Starling | 55846 | 2024 |
| bird | Sylvia | a Sylvia species (unidentified) | 3 | 2023 |
| bird | Sylvia atricapilla | Blackcap | 36615 | 2024 |
| bird | Sylvia borin | Garden Warbler | 2432 | 2023 |
| bird | Sylviidae | a warbler (sylviidae species unidentified) | 16 | 2013 |
| bird | Syrmaticus reevesii | Reeves's Pheasant | 1 | 2018 |
| booklouse or barklouse | Stenopsocus immaculatus (sensu lato) | a booklouse or barklouse | 3 | 2009 |
| bug | Salda littoralis | a shore bug | 1 | 2015 |
| bug | Saldula orthochila | a shore bug | 1 | 2015 |
| bug | Saldula pallipes | a shore bug | 1 | 1978 |
| bug | Saldula palustris | a shore bug | 11 | 2022 |
| bug | Saldula pilosella | a shore bug | 5 | 2015 |
| bug | Saldula saltatoria | Common Shorebug | 16 | 2021 |
| bug | Sardius argus | a leafhopper | 1 | 2019 |
| bug | Schizaphis (Schizaphis) graminum | an aphid | 1 | 2008 |
| bug | Sciocoris (Sciocoris) cursitans | Sandrunner | 22 | 2023 |
| bug | Scolopostethus | a Scolopostethus species (unidentified) | 1 | 2016 |
| bug | Scolopostethus affinis | a ground bug | 18 | 2021 |
| bug | Scolopostethus decoratus | a ground bug | 3 | 1999 |
| bug | Scolopostethus grandis | a ground bug | 9 | 2022 |
| bug | Scolopostethus pictus | a ground bug | 1 | 2005 |
| bug | Scolopostethus puberulus | a ground bug | 4 | 2018 |
| bug | Scolopostethus thomsoni | a ground bug | 53 | 2022 |
| bug | Sehirus luctuosus | a shield bug | 13 | 2023 |
| bug | Sigara | a Sigara waterman (unidentified) | 77 | 2013 |
| bug | Sigara (Halicorixa) stagnalis | a waterboatman | 5 | 2002 |
| bug | Sigara (Pseudovermicorixa) nigrolineata | a waterboatman | 21 | 2003 |
| bug | Sigara (Retrocorixa) semistriata | a waterboatman | 4 | 2004 |
| bug | Sigara (Sigara) dorsalis | a waterboatman | 97 | 2013 |
| bug | Sigara (Subsigara) distincta | a waterboatman | 15 | 2004 |
| bug | Sigara (Subsigara) falleni | a waterboatman | 29 | 2018 |
| bug | Sigara (Subsigara) fossarum | a waterboatman | 31 | 2013 |
| bug | Sigara (Vermicorixa) lateralis | a waterboatman | 40 | 2020 |
| bug | Siphoninus phillyreae | Ash Whitefly | 1 | 2018 |
| bug | Sitobion | a Sitobion aphid (unidentified) | 1 | 2014 |
| bug | Sitobion (Sitobion) avenae | Grain Aphid | 34 | 1985 |
| bug | Sitobion (Sitobion) fragariae | Blackberry-Cereal Aphid | 43 | 2008 |
| bug | Spanioneura fonscolombii | a jumping plantlouse | 2 | 2015 |
| bug | Staticobium staticis | an aphid | 1 | 2022 |
| bug | Stenocranus major | a planthopper | 1 | 2004 |
| bug | Stenocranus minutus | a planthopper | 13 | 2022 |
| bug | Stenodema | a Stenodema species (unidentified) | 2 | 2015 |
| bug | Stenodema (Brachystira) calcarata | a plantbug or grassbug | 73 | 2022 |
| bug | Stenodema (Stenodema) holsata | a plantbug or grassbug | 5 | 2012 |
| bug | Stenodema (Stenodema) laevigata | a plantbug or grassbug | 348 | 2023 |
| bug | Stenotus binotatus | Timothy Grassbug | 174 | 2023 |
| bug | Sthenarus rotermundi | a plantbug or grassbug | 1 | 2021 |
| bug | Stictopleurus abutilon | a ground bug | 3 | 2023 |
| bug | Stictopleurus punctatonervosus | a ground bug | 5 | 2022 |
| bug | Streptanus aemulans | a leafhopper | 2 | 2019 |
| bug | Streptanus sordidus | a leafhopper | 6 | 2023 |
| bug | Stygnocoris fuligineus | a ground bug | 5 | 2019 |
| bug | Stygnocoris rusticus | a ground bug | 5 | 2020 |
| bug | Stygnocoris sabulosus | a ground bug | 21 | 2021 |
| caddis fly | Sericostoma personatum | a caddisfly | 26 | 2022 |
| caddis fly | Sericostomatidae | a Sericostomatidae caddisfly (unidentified) | 4 | 2000 |
| caddis fly | Silo pallipes | a caddisfly | 2 | 2019 |
| caddis fly | Stenophylax | a Stenophylax caddisfly (unidentified) | 3 | 2023 |
| caddis fly | Stenophylax or a Micropterna (unidentified) | a Stenoflax or a Micropterna caddisfly (unidentified) | 1 | 2021 |
| caddis fly | Stenophylax permistus | a caddisfly | 31 | 2022 |
| caddis fly | Synagapetus dubitans | a caddisfly | 1 | 2019 |
| centipede | Scutigera coleoptrata | House Centipede | 7 | 2023 |
| centipede | Strigamia acuminata | Shorter Red Centipede | 2 | 1994 |
| centipede | Strigamia crassipes | Longer Red Centipede | 2 | 1999 |
| centipede | Strigamia maritima | Maritime Centipede | 2 | 1978 |
| clubmoss and quillworts | Selaginella kraussiana | Kraus's Clubmoss | 5 | 2023 |
| cockroach | Supella longipalpa | Brown-banded Cockroach | 1 | 2017 |
| crustacean | Sacculina carcini | a crustacean | 1 | 1938 |
| crustacean | Schistomysis spiritus | a crustacean | 1 | 1939 |
| crustacean | Semibalanus balanoides | Acorn barnacle | 8 | 2014 |
| crustacean | Sphaeroma serratum | a crustacean | 4 | 1940 |
| diatom | Staurosira construens | a diatom | 1 | 2015 |
| diatom | Staurosira elliptica | a diatom | 2 | 2015 |
| diatom | Staurosirella pinnata | a diatom | 2 | 2015 |
| diatom | Surirella | a Surirella species (unidentified) | 1 | 2010 |
| diatom | Synedra | a Synedra species (unidentified) | 1 | 2010 |
| dragonfly, hawker or damselfly | Sympetrum | a darter dragonfly (unidentified) | 32 | 2018 |
| dragonfly, hawker or damselfly | Sympetrum danae | Black Darter | 9 | 2011 |
| dragonfly, hawker or damselfly | Sympetrum flaveolum | Yellow-winged Darter | 20 | 1995 |
| dragonfly, hawker or damselfly | Sympetrum fonscolombii | Red-veined Darter | 31 | 2020 |
| dragonfly, hawker or damselfly | Sympetrum sanguineum | Ruddy Darter | 379 | 2022 |
| dragonfly, hawker or damselfly | Sympetrum striolatum | Common Darter | 3698 | 2023 |
| fish | Salmo salar | Atlantic Salmon | 7 | 2008 |
| fish | Salmo trutta | Brown/Sea Trout | 5 | 2008 |
| fish | Salmo trutta subsp. fario | Brown Trout | 124 | 2022 |
| fish | Salmo trutta subsp. trutta | Sea Trout | 1 | 2002 |
| fish | Sardina pilchardus | Pilchard | 1 | 1639 |
| fish | Scardinius erythrophthalmus | Rudd | 14 | 2018 |
| fish | Scomber scombrus | Mackerel | 2 | 1940 |
| fish | Scophthalmus maximus | Turbot | 5 | 2008 |
| fish | Scophthalmus rhombus | Brill | 2 | 1938 |
| fish | Scyliorhinus canicula | Lesser Spotted Dogfish | 6 | 2017 |
| fish | Scyliorhinus stellaris | Nursehound | 3 | 2017 |
| fish | Solea solea | Sole | 14 | 2015 |
| fish | Spinachia spinachia | Sea (Fifteen-spined) Stickleback | 2 | 1938 |
| fish | Spondyliosoma cantharus | Black Sea-bream | 1 | 1938 |
| fish | Sprattus sprattus | Sprat | 9 | 1941 |
| fish | Squalius cephalus | Chub | 35 | 2019 |
| fish | Squalus acanthias | Spurdog | 3 | 2012 |
| fish | Squatina squatina | Angel shark | 1 | 1939 |
| fish | Symphodus melops | Corkwing Wrasse | 1 | 1938 |
| fish | Syngnathus acus | Greater Pipefish | 1 | 1940 |
| flea | Spilopsyllus cuniculi | rabbit flea | 1 | 1976 |
| fungus | Sarcomyxa serotina | a basidiomycete fungus | 11 | 2014 |
| fungus | Sarcopyrenia gibba var. geisleri | a lichen | 2 | 2011 |
| fungus | Sarcoscypha | a Sarcoscypha species (unidentified) | 5 | 2017 |
| fungus | Sarcoscypha austriaca | Scarlet Elf Cup | 66 | 2024 |
| fungus | Sarcoscypha coccinea | a fungus | 18 | 2015 |
| fungus | Sawadaea bicornis | a conidial powdery mildew | 14 | 2014 |
| fungus | Sawadaea tulasnei | a fungus | 2 | 2022 |
| fungus | Schizophyllum commune | a basidiomycete fungus | 9 | 2023 |
| fungus | Schizopora paradoxa | Split Porecrust | 67 | 2020 |
| fungus | Scleroderma | an Scleroderma earthball (unidentified) | 1 | 2006 |
| fungus | Scleroderma areolatum | Leopard-spotted Earthball | 54 | 2013 |
| fungus | Scleroderma bovista | Potato Earthball | 2 | 2009 |
| fungus | Scleroderma citrinum | Common Earthball | 81 | 2014 |
| fungus | Scleroderma spadiceum | a fungus | 1 | 2000 |
| fungus | Scleroderma verrucosum | Scaly Earthball | 36 | 2023 |
| fungus | Scutellinia scutellata | a fungus | 13 | 2012 |
| fungus | Scutellinia subhirtella | a fungus | 1 | 2003 |
| fungus | Scutellinia umbrorum | a fungus | 3 | 2012 |
| fungus | Sebacina incrustans | a basidiomycete fungus | 5 | 2008 |
| fungus | Seifertia azaleae | a fungus | 2 | 2010 |
| fungus | Septoria | a Septoria species (unidentified) | 1 | 1998 |
| fungus | Septoria chamaecysti | a fungus | 1 | 1998 |
| fungus | Septoria clematidis | a fungus | 1 | 2008 |
| fungus | Septoria convolvuli | a fungus | 2 | 2008 |
| fungus | Septoria cornicola | a fungus | 6 | 2013 |
| fungus | Septoria scabiosicola | a fungus | 36 | 2023 |
| fungus | Septoria sorbi | a fungus | 2 | 2001 |
| fungus | Septoria stachydis | a late blight fungus | 1 | 2011 |
| fungus | Simocybe centunculus | a fungus | 1 | 2013 |
| fungus | Simocybe centunculus var. centunculus | Dingy Twiglet | 7 | 2002 |
| fungus | Simocybe haustellaris | an agaric | 3 | 2008 |
| fungus | Simocybe sumptuosa | an agaric | 13 | 2013 |
| fungus | Sistotrema brinkmannii | a basidiomycete fungus | 1 | 2010 |
| fungus | Skeletocutis amorpha | a basidiomycete fungus | 5 | 2013 |
| fungus | Skeletocutis lenis | a basidiomycete fungus | 1 | 1999 |
| fungus | Skeletocutis semipileata | Hazel Bracket | 18 | 2016 |
| fungus | Sowerbyella radiculata | a fungus | 2 | 2012 |
| fungus | Sparassis crispa | Cauliflower Fungus | 4 | 2013 |
| fungus | Spermosporina aricola | a fungus | 3 | 2015 |
| fungus | Sphaceloma | a Sphaceloma species (unidentified) | 1 | 2018 |
| fungus | Sphaerotheca erigerontis | a fungus | 1 | 2011 |
| fungus | Sphaerulina azaleae | a fungus | 5 | 2013 |
| fungus | Sphaerulina hyperici | a fungus | 1 | 1998 |
| fungus | Sphaerulina rehmiana | a fungus | 2 | 2010 |
| fungus | Sphinctrina turbinata | a fungus | 1 | 1996 |
| fungus | Spinellus fusiger | a zygomycete fungus | 2 | 2011 |
| fungus | Sporendocladia fumosa | a fungus | 1 | 2012 |
| fungus | Steccherinum fimbriatum | a basidiomycete fungus | 2 | 2018 |
| fungus | Steccherinum ochraceum | a basidiomycete fungus | 5 | 2020 |
| fungus | Stenocybe pullatula | a fungus | 1 | 2018 |
| fungus | Stephanospora caroticolor | Carroty False Truffle | 1 | 1959 |
| fungus | Stereum | a Stereum species (unidentified) | 5 | 2023 |
| fungus | Stereum complicatum | a fungus | 1 | 2000 |
| fungus | Stereum gausapatum | Bleeding Oak Crust | 32 | 2023 |
| fungus | Stereum hirsutum | Hairy Curtain Crust | 223 | 2023 |
| fungus | Stereum ochraceoflavum | a basidiomycete fungus | 13 | 2005 |
| fungus | Stereum rameale | a basidiomycete fungus | 7 | 2020 |
| fungus | Stereum rugosum | Bleeding Broadleaf Crust | 74 | 2020 |
| fungus | Stereum sanguinolentum | Bleeding Conifer Crust | 7 | 2020 |
| fungus | Stereum subtomentosum | Yellowing Curtain Crust | 31 | 2014 |
| fungus | Stictis radiata | a fungus | 1 | 2000 |
| fungus | Stigmidium | a Stigmidium species (unidentified) | 1 | 2012 |
| fungus | Strigula jamesii | an ascomycete fungus | 1 | 2018 |
| fungus | Strigula taylorii | an ascomycete fungus | 3 | 2010 |
| fungus | Strobilurus esculentus | a basidiomycete fungus | 3 | 2014 |
| fungus | Stropharia | a Stropharia species (unidentified) | 1 | 2016 |
| fungus | Stropharia aeruginosa | Verdigris Agaric | 9 | 2011 |
| fungus | Stropharia caerulea | Blue Roundhead | 70 | 2023 |
| fungus | Stropharia coronilla | an agaric | 43 | 2013 |
| fungus | Stropharia inuncta | an agaric | 27 | 2013 |
| fungus | Stropharia luteonitens | an agaric | 1 | 2003 |
| fungus | Stropharia pseudocyanea | an agaric | 19 | 2014 |
| fungus | Stropharia semiglobata | Dung Roundhead | 146 | 2023 |
| fungus | Stropholoma aurantiacum | an agaric | 2 | 2015 |
| fungus | Strossmayeria basitricha | an ascomycete fungus | 1 | 2013 |
| fungus | Suillus bovinus | a bolete | 4 | 1999 |
| fungus | Suillus collinitus | a bolete | 1 | 2015 |
| fungus | Suillus granulatus | a bolete | 63 | 2014 |
| fungus | Suillus grevillei | Larch Bolete | 22 | 2014 |
| fungus | Suillus luteus | Slippery Jack | 3 | 2006 |
| fungus | Suillus viscidus | a bolete | 4 | 2009 |
| fungus | Synchytrium mercurialis | a chytridiomycete fungus | 1 | 2017 |
| fungus | Synchytrium taraxaci | Dandelion Chytrid | 1 | 2016 |
| grasshopper, cricket or true cricket | Stenobothrus lineatus | Stripe-Winged Grasshopper | 65 | 2016 |
| leech, flatworm or ribbon worm | Schmidtea | a Schmidtea marine flatworm (unidentified) | 3 | 2023 |
| leech, flatworm or ribbon worm | Schmidtea lugubris | a flatworm | 3 | 2012 |
| leech, flatworm or ribbon worm | Schmidtea polychroa | a flatworm | 2 | 1997 |
| lichen | Sarcogyne regularis | a lichen | 8 | 2014 |
| lichen | Scoliciosporum chlorococcum | a lichen | 9 | 2018 |
| lichen | Scoliciosporum umbrinum | a lichen | 9 | 2004 |
| lichen | Solenopsora candicans | a lichen | 11 | 2018 |
| lichen | Squamarina cartilaginea | a lichen | 9 | 2020 |
| lichen | Staurothele | a Staurothele species (unidentified) | 1 | 2002 |
| lichen | Staurothele caesia | a lichen | 2 | 2018 |
| lichen | Staurothele guestphalica | a lichen | 2 | 2018 |
| lichen | Staurothele rupifraga | a lichen | 1 | 2018 |
| lichen | Strangospora pinicola | a lichen | 1 | 1991 |
| lichen | Synalissa ramulosa | a lichen | 3 | 2005 |
| liverwort | Saccogyna viticulosa | Straggling Pouchwort | 1 | 2019 |
| liverwort | Scapania aspera | Rough Earwort | 8 | 2023 |
| liverwort | Scapania nemorea | Grove Earwort | 1 | 2019 |
| liverwort | Solenostoma gracillimum | Crenulated Flapwort | 2 | 1963 |
| mammal | Sciurus | a squirrel (unidentified) | 10 | 2021 |
| mammal | Sciurus carolinensis | Grey Squirrel | 3727 | 2024 |
| mammal | Sorex | a shrew (unidentified) | 72 | 2022 |
| mammal | Sorex araneus | Common Shrew | 208 | 2023 |
| mammal | Sorex minutus | Pygmy Shrew | 79 | 2024 |
| mammal | Soricidae | a Soricidae species (unidentified) | 1 | 2023 |
| mammal | Sus scrofa | Wild Boar | 3 | 2005 |
| mayfly | Serratella ignita | a mayfly | 12 | 2021 |
| millipede | Stosatea italica | a blaniulid snake millipede | 1 | 2022 |
| mollusc | Scrobicularia plana | Peppery Furrow Shell | 3 | 1939 |
| mollusc | Segmentina | a Segmentina species (unidentified) | 1 | 2016 |
| mollusc | Selenochlamys ysbryda | Ghost Slug | 3 | 2020 |
| mollusc | Sepia officinalis | Common Cuttlefish | 15 | 2019 |
| mollusc | Sepia orbignyana | a mollusc | 1 | 2019 |
| mollusc | Sepiola atlantica | Little Cuttlefish | 2 | 1938 |
| mollusc | Snails | a snail (unidentified) | 118 | 2023 |
| mollusc | Sphaeriidae | a Sphaeriidae orb mussel (unidentified) | 49 | 2018 |
| mollusc | Sphaerium | an Sphaerium orb mussel (unidentified) | 58 | 2013 |
| mollusc | Sphaerium corneum | Horny Orb Mussel | 148 | 2023 |
| mollusc | Sphaerium lacustre | Lake Orb Mussel | 56 | 2015 |
| mollusc | Sphaerium nucleus | a mollusc | 4 | 2012 |
| mollusc | Stagnicola fuscus | a mollusc | 107 | 2013 |
| mollusc | Stagnicola palustris/fuscus/corvus (agg.) | Marsh Pond Snail | 117 | 2007 |
| mollusc | Stylommatophora | a Stylommatophora species (unidentified) | 2 | 2023 |
| mollusc | Succinea | a Succinea species (unidentified) | 4 | 1998 |
| mollusc | Succinea putris | Amber Snail | 76 | 2020 |
| mollusc | Succineidae | a Succineidae species (unidentified) | 73 | 2014 |
| moss | Sanionia uncinata | Sickle-leaved Hook-moss | 3 | 2007 |
| moss | Schistidium apocarpum | Sessile Grimmia | 10 | 2010 |
| moss | Schistidium apocarpum (sensu lato) | a moss | 5 | 2004 |
| moss | Schistidium crassipilum | Thickpoint Grimmia | 65 | 2023 |
| moss | Sciuro-hypnum populeum | Matted Feather-moss | 10 | 2023 |
| moss | Scleropodium | a Scleropodium feather-moss (unidentified) | 2 | 1998 |
| moss | Scleropodium cespitans | Tufted Feather-moss | 1 | 1998 |
| moss | Scorpidium scorpioides | Hooked Scorpion-moss | 1 | 1995 |
| moss | Scorpiurium circinatum | Curving Feather-moss | 5 | 2023 |
| moss | Seligeria acutifolia | Sharp Rock-bristle | 2 | 1990 |
| moss | Seligeria pusilla | Dwarf Rock-bristle | 5 | 2016 |
| moss | Sematophyllum substrumulosum | Bark Signal-moss | 1 | 2018 |
| moss | Sphagnum fimbriatum | Fringed Bog-moss | 2 | 2006 |
| moss | Sphagnum palustre | a moss | 1 | 2006 |
| moss | Streblotrichum convolutum var. convolutum | a Lesser Bird's-claw Beard-moss | 7 | 2023 |
| moss | Syntrichia | a Syntrichia species (unidentified) | 3 | 2023 |
| moss | Syntrichia laevipila | Small Hairy Screw-moss | 50 | 2023 |
| moss | Syntrichia laevipila var. laevipila | a small hairy screw-moss | 1 | 1991 |
| moss | Syntrichia montana | Intermediate Screw-moss | 94 | 2023 |
| moss | Syntrichia papillosa | Marble Screw-moss | 23 | 2023 |
| moss | Syntrichia ruralis | Great Hairy Screw-moss | 46 | 2023 |
| moss | Syntrichia ruralis (sensu lato) | a moss | 7 | 2011 |
| moss | Syntrichia ruralis var. ruraliformis | Sand-hill Screw-moss | 5 | 2020 |
| moth or butterfly - butterfly | Satyridae | a Satyridae species (unidentified) | 4 | 2009 |
| moth or butterfly - butterfly | Satyrium w-album | White-letter Hairstreak | 333 | 2022 |
| moth or butterfly - butterfly | Speyeria aglaja | Dark Green Fritillary | 416 | 2021 |
| moth or butterfly - butterfly | Speyeria aglaja aglaja | Dark Green Fritillary form aglaja | 85 | 2011 |
| moth or butterfly - macro moth | Saturnia pavonia | Emperor (Moth) | 7 | 2013 |
| moth or butterfly - macro moth | Schrankia costaestrigalis | Pinion-streaked Snout | 91 | 2023 |
| moth or butterfly - macro moth | Schrankia taenialis | White-lined Snout | 15 | 2014 |
| moth or butterfly - macro moth | Scoliopteryx libatrix | Herald | 468 | 2022 |
| moth or butterfly - macro moth | Scopula | a Scopula species (unidentified) | 2 | 2013 |
| moth or butterfly - macro moth | Scopula emutaria | Rosy Wave | 2 | 1979 |
| moth or butterfly - macro moth | Scopula floslactata | a moth | 26 | 2021 |
| moth or butterfly - macro moth | Scopula floslactata form floslactata | Cream Wave | 94 | 2020 |
| moth or butterfly - macro moth | Scopula imitaria | Small Blood-vein | 1193 | 2023 |
| moth or butterfly - macro moth | Scopula immutata | Lesser Cream Wave | 45 | 2021 |
| moth or butterfly - macro moth | Scopula marginepunctata | Mullein Wave | 31 | 2022 |
| moth or butterfly - macro moth | Scopula ternata | Smoky Wave | 2 | 2019 |
| moth or butterfly - macro moth | Scotopteryx bipunctaria | Chalk Carpet | 65 | 2022 |
| moth or butterfly - macro moth | Scotopteryx chenopodiata | Shaded Broad-bar | 683 | 2022 |
| moth or butterfly - macro moth | Scotopteryx luridata plumbaria | July Belle | 5 | 1996 |
| moth or butterfly - macro moth | Scotopteryx mucronata umbrifera | Lead Belle | 10 | 2014 |
| moth or butterfly - macro moth | Selenia dentaria | Early Thorn | 1700 | 2023 |
| moth or butterfly - macro moth | Selenia lunularia | Lunar Thorn | 31 | 2010 |
| moth or butterfly - macro moth | Selenia tetralunaria | Purple Thorn | 339 | 2022 |
| moth or butterfly - macro moth | Sesia apiformis | Hornet Moth | 16 | 2021 |
| moth or butterfly - macro moth | Sesia bembeciformis | Lunar Hornet Moth | 35 | 2022 |
| moth or butterfly - macro moth | Sesiidae | a clearwing moth (unidentified) | 2 | 2013 |
| moth or butterfly - macro moth | Sideridis reticulata | Bordered Gothic | 1 | 1969 |
| moth or butterfly - macro moth | Sideridis rivularis | Campion | 61 | 2022 |
| moth or butterfly - macro moth | Sideridis turbida | White Colon | 9 | 2019 |
| moth or butterfly - macro moth | Smerinthus ocellata | Eyed Hawk-moth | 415 | 2023 |
| moth or butterfly - macro moth | Spaelotis ravida | Stout Dart | 6 | 1991 |
| moth or butterfly - macro moth | Sphinx ligustri | Privet Hawk-moth | 1088 | 2023 |
| moth or butterfly - macro moth | Sphinx pinastri | Pine Hawk-moth | 7 | 2020 |
| moth or butterfly - macro moth | Spilosoma lubricipeda | White Ermine | 1352 | 2023 |
| moth or butterfly - macro moth | Spilosoma lutea | Buff Ermine | 3358 | 2023 |
| moth or butterfly - macro moth | Spilosoma urticae | Water Ermine | 1 | 2017 |
| moth or butterfly - macro moth | Spodoptera exigua | Small Mottled Willow | 96 | 2022 |
| moth or butterfly - macro moth | Standfussiana lucernea | Northern Rustic | 4 | 1963 |
| moth or butterfly - macro moth | Stauropus fagi | Lobster Moth | 205 | 2023 |
| moth or butterfly - macro moth | Stilbia anomala | Anomalous | 7 | 1995 |
| moth or butterfly - macro moth | Subacronicta megacephala | Poplar Grey | 531 | 2023 |
| moth or butterfly - macro moth | Synanthedon andrenaeformis | Orange-tailed Clearwing | 40 | 2022 |
| moth or butterfly - macro moth | Synanthedon culiciformis | Large Red-belted Clearwing | 2 | 2017 |
| moth or butterfly - macro moth | Synanthedon flaviventris | Sallow Clearwing | 4 | 2014 |
| moth or butterfly - macro moth | Synanthedon formicaeformis | Red-tipped Clearwing | 15 | 2021 |
| moth or butterfly - macro moth | Synanthedon myopaeformis | Red-belted Clearwing | 58 | 2023 |
| moth or butterfly - macro moth | Synanthedon tipuliformis | Currant Clearwing | 44 | 2022 |
| moth or butterfly - macro moth | Synanthedon vespiformis | Yellow-legged Clearwing | 32 | 2021 |
| moth or butterfly - micro moth | Salebriopsis albicilla | a pyralid moth | 13 | 2005 |
| moth or butterfly - micro moth | Schreckensteinia festaliella | a micro-moth | 10 | 2022 |
| moth or butterfly - micro moth | Scoparia | a Scoparia species (unidentified) | 18 | 2017 |
| moth or butterfly - micro moth | Scoparia ambigualis | Common Grey | 732 | 2022 |
| moth or butterfly - micro moth | Scoparia basistrigalis | a pyralid moth | 13 | 2019 |
| moth or butterfly - micro moth | Scoparia pyralella | Meadow Grey | 131 | 2022 |
| moth or butterfly - micro moth | Scoparia subfusca | a pyralid moth | 137 | 2022 |
| moth or butterfly - micro moth | Scrobipalpa | a Scrobipalpa species (unidentified) | 1 | 2023 |
| moth or butterfly - micro moth | Scrobipalpa acuminatella | Pointed Groundling | 55 | 2023 |
| moth or butterfly - micro moth | Scrobipalpa costella | a micro-moth | 83 | 2022 |
| moth or butterfly - micro moth | Scrobipalpa nitentella | a micro-moth | 2 | 2019 |
| moth or butterfly - micro moth | Scrobipalpa obsoletella | a micro-moth | 1 | 1999 |
| moth or butterfly - micro moth | Scrobipalpa ocellatella | Beet Moth | 22 | 2022 |
| moth or butterfly - micro moth | Scythris crassiuscula | a micro-moth | 4 | 1999 |
| moth or butterfly - micro moth | Scythris grandipennis | a micro-moth | 1 | 2001 |
| moth or butterfly - micro moth | Scythris picaepennis | a micro-moth | 5 | 2001 |
| moth or butterfly - micro moth | Scythropia crataegella | Hawthorn Moth | 137 | 2022 |
| moth or butterfly - micro moth | Semioscopis avellanella | a micro-moth | 6 | 2014 |
| moth or butterfly - micro moth | Semioscopis steinkellneriana | a micro-moth | 26 | 2020 |
| moth or butterfly - micro moth | Sitochroa palealis | a pyralid moth | 30 | 2020 |
| moth or butterfly - micro moth | Sitochroa verticalis | a pyralid moth | 43 | 2013 |
| moth or butterfly - micro moth | Sophronia semicostella | a micro-moth | 7 | 2022 |
| moth or butterfly - micro moth | Sorhagenia lophyrella | a micro-moth | 2 | 1999 |
| moth or butterfly - micro moth | Spatalistis bifasciana | a tortrix moth | 14 | 2020 |
| moth or butterfly - micro moth | Spilonota | a Spilonota species (unidentified) | 6 | 2021 |
| moth or butterfly - micro moth | Spilonota laricana | a tortrix moth | 8 | 2022 |
| moth or butterfly - micro moth | Spilonota ocellana | Bud Moth | 247 | 2022 |
| moth or butterfly - micro moth | Spuleria flavicaput | a micro-moth | 11 | 2022 |
| moth or butterfly - micro moth | Stathmopoda pedella | a micro-moth | 11 | 2022 |
| moth or butterfly - micro moth | Stenolechia gemmella | a micro-moth | 2 | 2012 |
| moth or butterfly - micro moth | Stenoptilia bipunctidactyla | a plume moth | 67 | 2020 |
| moth or butterfly - micro moth | Stenoptilia pterodactyla | a plume moth | 51 | 2022 |
| moth or butterfly - micro moth | Stenoptilia zophodactylus | a plume moth | 7 | 2012 |
| moth or butterfly - micro moth | Stephensia brunnichella | a micro-moth | 9 | 2016 |
| moth or butterfly - micro moth | Stigmella | a Stigmella species (unidentified) | 8 | 2023 |
| moth or butterfly - micro moth | Stigmella aceris | a micro-moth | 6 | 2022 |
| moth or butterfly - micro moth | Stigmella aeneofasciella | a micro-moth | 1 | 1920 |
| moth or butterfly - micro moth | Stigmella alnetella | a micro-moth | 4 | 2021 |
| moth or butterfly - micro moth | Stigmella anomalella | Rosy Leaf Miner | 36 | 2022 |
| moth or butterfly - micro moth | Stigmella assimilella | a micro-moth | 5 | 2020 |
| moth or butterfly - micro moth | Stigmella atricapitella | a micro-moth | 23 | 2023 |
| moth or butterfly - micro moth | Stigmella aurella | Golden Pigmy | 291 | 2023 |
| moth or butterfly - micro moth | Stigmella aurella form nitens | False Golden Pigmy | 1 | 1972 |
| moth or butterfly - micro moth | Stigmella basiguttella | a micro-moth | 6 | 2022 |
| moth or butterfly - micro moth | Stigmella betulicola | a moth | 2 | 2019 |
| moth or butterfly - micro moth | Stigmella betulicola form nanivora | a micro-moth | 1 | 1995 |
| moth or butterfly - micro moth | Stigmella catharticella | a micro-moth | 13 | 2023 |
| moth or butterfly - micro moth | Stigmella centifoliella | a micro-moth | 7 | 2021 |
| moth or butterfly - micro moth | Stigmella confusella | a micro-moth | 6 | 2019 |
| moth or butterfly - micro moth | Stigmella continuella | a micro-moth | 6 | 2020 |
| moth or butterfly - micro moth | Stigmella crataegella | a micro-moth | 14 | 2021 |
| moth or butterfly - micro moth | Stigmella filipendulae | a micro-moth | 1 | 1997 |
| moth or butterfly - micro moth | Stigmella floslactella | a micro-moth | 112 | 2023 |
| moth or butterfly - micro moth | Stigmella glutinosae | a micro-moth | 2 | 2016 |
| moth or butterfly - micro moth | Stigmella hemargyrella | a micro-moth | 58 | 2023 |
| moth or butterfly - micro moth | Stigmella hybnerella | a micro-moth | 48 | 2023 |
| moth or butterfly - micro moth | Stigmella incognitella | a micro-moth | 3 | 2022 |
| moth or butterfly - micro moth | Stigmella lapponica | a micro-moth | 7 | 2016 |
| moth or butterfly - micro moth | Stigmella lemniscella | a micro-moth | 48 | 2023 |
| moth or butterfly - micro moth | Stigmella luteella | a micro-moth | 15 | 2022 |
| moth or butterfly - micro moth | Stigmella malella | Apple Pygmy | 3 | 2020 |
| moth or butterfly - micro moth | Stigmella microtheriella | a micro-moth | 145 | 2023 |
| moth or butterfly - micro moth | Stigmella nylandriella | a micro-moth | 2 | 2005 |
| moth or butterfly - micro moth | Stigmella obliquella | a micro-moth | 16 | 2022 |
| moth or butterfly - micro moth | Stigmella oxyacanthella | a micro-moth | 21 | 2022 |
| moth or butterfly - micro moth | Stigmella paradoxa | a micro-moth | 4 | 2011 |
| moth or butterfly - micro moth | Stigmella perpygmaeella | a micro-moth | 26 | 2023 |
| moth or butterfly - micro moth | Stigmella plagicolella | a micro-moth | 56 | 2022 |
| moth or butterfly - micro moth | Stigmella regiella | a micro-moth | 19 | 2022 |
| moth or butterfly - micro moth | Stigmella roborella | a micro-moth | 9 | 2022 |
| moth or butterfly - micro moth | Stigmella ruficapitella | a micro-moth | 21 | 2020 |
| moth or butterfly - micro moth | Stigmella sakhalinella | a micro-moth | 12 | 2022 |
| moth or butterfly - micro moth | Stigmella salicis | a micro-moth | 24 | 2020 |
| moth or butterfly - micro moth | Stigmella samiatella | a micro-moth | 7 | 2020 |
| moth or butterfly - micro moth | Stigmella sorbi | a micro-moth | 1 | 2000 |
| moth or butterfly - micro moth | Stigmella speciosa | a micro-moth | 14 | 2019 |
| moth or butterfly - micro moth | Stigmella splendidissimella | a micro-moth | 43 | 2023 |
| moth or butterfly - micro moth | Stigmella suberivora | a micro-moth | 18 | 2020 |
| moth or butterfly - micro moth | Stigmella tiliae | a micro-moth | 25 | 2023 |
| moth or butterfly - micro moth | Stigmella tityrella | a micro-moth | 101 | 2022 |
| moth or butterfly - micro moth | Stigmella trimaculella | a micro-moth | 18 | 2022 |
| moth or butterfly - micro moth | Stigmella ulmivora | a micro-moth | 21 | 2023 |
| moth or butterfly - micro moth | Stigmella viscerella | a micro-moth | 7 | 2020 |
| moth or butterfly - micro moth | Strophedra nitidana | a tortrix moth | 3 | 2017 |
| moth or butterfly - micro moth | Strophedra weirana | a tortrix moth | 13 | 2022 |
| moth or butterfly - micro moth | Swammerdamia | a Swammerdamia species (unidentified) | 1 | 2010 |
| moth or butterfly - micro moth | Swammerdamia caesiella | a micro-moth | 28 | 2022 |
| moth or butterfly - micro moth | Swammerdamia pyrella | a micro-moth | 197 | 2022 |
| moth or butterfly - micro moth | Synaphe punctalis | a pyralid moth | 2 | 2023 |
| moth or butterfly - micro moth | Syncopacma | a Syncopacma species (unidentified) | 1 | 2019 |
| moth or butterfly - micro moth | Syncopacma larseniella | a micro-moth | 21 | 2022 |
| moth or butterfly - micro moth | Syncopacma polychromella | a micro-moth | 2 | 2015 |
| moth or butterfly - micro moth | Syncopacma taeniolella | a micro-moth | 12 | 2021 |
| moth or butterfly - micro moth | Syndemis musculana | Dark-barred Twist | 250 | 2022 |
| moth or butterfly - micro moth | Syndemis musculana subsp. musculana | a tortrix moth | 5 | 2015 |
| moth or butterfly - moth (macro or micro not listed) moth | Sphingidae | a hawk-moth (unidentified) | 8 | 2016 |
| plant | Sagina | a pearlwort (unidentified) | 3 | 2023 |
| plant | Sagina apetala | Annual Pearlwort | 90 | 2020 |
| plant | Sagina apetala subsp. apetala | an annual pearlwort | 159 | 2019 |
| plant | Sagina apetala subsp. erecta | Fringed Pearlwort | 87 | 2019 |
| plant | Sagina apetala subsp. filicaulis | a Plant | 3 | 2020 |
| plant | Sagina maritima | Sea Pearlwort | 49 | 2016 |
| plant | Sagina nodosa | Knotted Pearlwort | 18 | 2018 |
| plant | Sagina procumbens | Procumbent Pearlwort | 749 | 2023 |
| plant | Sagittaria latifolia | Duck-potato | 1 | 1998 |
| plant | Sagittaria sagittifolia | Arrowhead | 210 | 2021 |
| plant | Salicornia | a glasswort (unidentified) | 59 | 2012 |
| plant | Salicornia dolichostachya | Long-spiked Glasswort | 15 | 1998 |
| plant | Salicornia europaea | Common Glasswort | 20 | 2014 |
| plant | Salicornia europaea agg. | a glasswort | 6 | 2017 |
| plant | Salicornia fragilis | Yellow Glasswort | 5 | 1996 |
| plant | Salicornia obscura | Glaucous Glasswort | 4 | 1991 |
| plant | Salicornia ramosissima | Purple Glasswort | 51 | 2014 |
| plant | Salix | a willow (unidentified) | 1269 | 2023 |
| plant | Salix alba | White Willow | 544 | 2023 |
| plant | Salix alba 'Britzensis' | a willow | 1 | 2016 |
| plant | Salix alba x babylonica = S. x sepulcralis | Weeping Willow | 30 | 2019 |
| plant | Salix aurita | Eared Willow | 12 | 2014 |
| plant | Salix babylonica | a Weeping Willow | 88 | 2023 |
| plant | Salix caprea | Goat willow | 791 | 2023 |
| plant | Salix caprea subsp. caprea | a goat willow (occurs in Avon) | 900 | 2017 |
| plant | Salix caprea x cinerea = S. x reichardtii | a goat willow (often mistaken for Salix caprea spp. caprea) | 154 | 2021 |
| plant | Salix cinerea | Grey Willow | 586 | 2023 |
| plant | Salix cinerea subsp. cinerea | a willow | 3 | 2023 |
| plant | Salix cinerea subsp. oleifolia | Rusty Willow | 804 | 2017 |
| plant | Salix daphnoides | European Violet-willow | 10 | 2013 |
| plant | Salix elaeagnos | Olive Willow | 2 | 1936 |
| plant | Salix euxina x alba = S. x fragilis | Crack Willow | 2158 | 2023 |
| plant | Salix euxina x alba x babylonica = S. x pendulina | Weeping Crack-willow | 1 | 2013 |
| plant | Salix euxina x alba x triandra = S. x alopecuroides | a willow | 2 | 1932 |
| plant | Salix matsudana | Contorted Willow | 2 | 2018 |
| plant | Salix pentandra | Bay Willow | 3 | 2000 |
| plant | Salix purpurea | Purple Willow | 19 | 2016 |
| plant | Salix purpurea x viminalis = S. x rubra | Green-leaved Willow | 3 | 2000 |
| plant | Salix repens | Creeping Willow | 2 | 1987 |
| plant | Salix (sallow) | a sallow (unidentified) | 63 | 2021 |
| plant | Salix triandra | Almond Willow | 46 | 2010 |
| plant | Salix viminalis | Osier | 266 | 2020 |
| plant | Salix viminalis x aurita = S. x fruticosa | Shrubby Osier | 1 | 1985 |
| plant | Salix viminalis x caprea = S. x smithiana | Broad-leaved Osier | 4 | 1999 |
| plant | Salix viminalis x caprea x cinerea = S. x calodendron | Holme Willow | 1 | 1990 |
| plant | Salix viminalis x cinerea = S. x holosericea | Silky-leaved Osier | 6 | 2014 |
| plant | Salix (weeping willow) | a weeping willow (unidentified) | 3 | 2023 |
| plant | Salix x mollissima nothovar. hippophaifolia | a willow | 1 | 1985 |
| plant | Salix x mollissima nothovar. undulata | a willow | 1 | 1985 |
| plant | Salix x pendulina subsp. pendulina | a Plant | 1 | 2023 |
| plant | Salix x sepulcralis 'Chrysocoma' | a Plant | 2 | 1939 |
| plant | Salsola kali | Saltwort | 7 | 2019 |
| plant | Salsola kali subsp. iberica | Spineless Saltwort | 8 | 1990 |
| plant | Salsola kali subsp. kali | Prickly Saltwort | 39 | 2019 |
| plant | Salvia | a Salvia species (unidentified) | 2 | 2023 |
| plant | Salvia nemorosa | Balkan Clary | 2 | 1933 |
| plant | Salvia officinalis | Sage | 14 | 2018 |
| plant | Salvia pratensis | Meadow Clary | 4 | 2004 |
| plant | Salvia reflexa | Mintweed | 5 | 1990 |
| plant | Salvia sclarea | Clary | 2 | 1995 |
| plant | Salvia verbenaca | Wild Clary | 206 | 2023 |
| plant | Salvia verticillata | Whorled Clary | 1 | 2002 |
| plant | Sambucus | a Sambucus species (unidentified) | 2 | 2023 |
| plant | Sambucus ebulus | Dwarf Elder | 23 | 2022 |
| plant | Sambucus nigra | Elder | 11552 | 2023 |
| plant | Sambucus nigra var. laciniata | Cut-leaved Elder | 1 | 2017 |
| plant | Sambucus racemosa | Red-berried Elder | 1 | 1999 |
| plant | Samolus valerandi | Brookweed | 153 | 2015 |
| plant | Sanguisorba | a Sanguisorba species (unidentified) | 5 | 2023 |
| plant | Sanguisorba officinalis | Great Burnet | 33 | 2017 |
| plant | Sanicula europaea | Sanicle | 550 | 2023 |
| plant | Saponaria officinalis | Soapwort | 102 | 2020 |
| plant | Sasa | a Sasa bamboo (unidentified) | 2 | 2007 |
| plant | Sasaella | a Sasaella bamboo species (unidentified) | 1 | 2014 |
| plant | Sasa palmata | Broad-leaved Bamboo | 2 | 2016 |
| plant | Sasa ramosa | Hairy Bamboo | 3 | 2013 |
| plant | Saxifraga | a Saxifraga species (unidentified) | 1 | 2014 |
| plant | Saxifraga cymbalaria | Celandine Saxifrage | 16 | 2015 |
| plant | Saxifraga granulata | Meadow Saxifrage | 23 | 2023 |
| plant | Saxifraga hirsuta | Kidney Saxifrage | 6 | 2009 |
| plant | Saxifraga stolonifera | Strawberry Saxifrage | 1 | 1995 |
| plant | Saxifraga tridactylites | Rue-leaved Saxifrage | 335 | 2023 |
| plant | Saxifraga umbrosa x spathularis = S. x urbium | Londonpride | 5 | 2010 |
| plant | Scabiosa | a Scabiosa species (unidentified) | 1 | 2007 |
| plant | Scabiosa columbaria | Small Scabious | 714 | 2023 |
| plant | Scabiosa sp. or Knautia sp. or Succisa sp. or centaurea sp. (unidentified scabious or knapweed or cornflower) | a scabious or knapweed or cornflower (unidentified) | 2 | 2011 |
| plant | Scabiosa sp. or Knautia sp. or Succisa sp. (unidentified scabious) | a scabious (unidentified) | 20 | 2018 |
| plant | Scandix iberica | a Plant | 3 | 1940 |
| plant | Scandix pecten-veneris | Shepherd's-needle | 44 | 2011 |
| plant | Schkuhria pinnata | Dwarf Marigold | 1 | 1940 |
| plant | Schoenoplectus lacustris | Common Club-rush | 161 | 2019 |
| plant | Schoenoplectus tabernaemontani | Grey Club-rush | 50 | 2014 |
| plant | Schoenus nigricans | Black Bog-rush | 22 | 2015 |
| plant | Scilla autumnalis | Autumn Squill | 14 | 2009 |
| plant | Scilla bifolia | Alpine Squill | 2 | 2019 |
| plant | Scilla bithynica | a squill | 8 | 2008 |
| plant | Scilla forbesii | Glory-of-the-snow | 5 | 2018 |
| plant | Scilla luciliae | Boissier's Glory-of-the-snow | 2 | 2017 |
| plant | Scilla siberica | Siberian Squill | 4 | 2019 |
| plant | Scilla verna | Spring Squill | 2 | 1985 |
| plant | Scirpoides holoschoenus | Round-headed Club-rush | 2 | 1928 |
| plant | Scirpus | a Scirpus species (unidentified) | 3 | 1999 |
| plant | Scirpus sylvaticus | Wood Club-rush | 13 | 2006 |
| plant | Scleranthus annuus | Annual Knawel | 7 | 1998 |
| plant | Scleranthus annuus subsp. annuus | an annual knawel | 8 | 2007 |
| plant | Scorzonera hispanica | Scorzonera | 1 | 2002 |
| plant | Scorzoneroides autumnalis | Autumn Hawkbit | 2037 | 2023 |
| plant | Scrophularia | a Figwort (unidentified) | 11 | 2023 |
| plant | Scrophularia auriculata | Water Figwort | 1485 | 2023 |
| plant | Scrophulariaceae | a Scrophulariaceae species (unidentified) | 1 | 2010 |
| plant | Scrophularia nodosa | Common Figwort | 1363 | 2023 |
| plant | Scutellaria altissima | Somerset Skullcap | 3 | 2018 |
| plant | Scutellaria galericulata | Skullcap | 150 | 2018 |
| plant | Scutellaria minor | Lesser Skullcap | 2 | 1993 |
| plant | Secale cereale | Rye | 5 | 2016 |
| plant | Securigera varia | Crown Vetch | 10 | 2008 |
| plant | Sedum | a Sedum species (unidentified) | 16 | 2023 |
| plant | Sedum acre | Biting Stonecrop | 1028 | 2023 |
| plant | Sedum album | White Stonecrop | 394 | 2023 |
| plant | Sedum anglicum | English Stonecrop | 7 | 2013 |
| plant | Sedum cepaea | a stonecrop | 1 | 2016 |
| plant | Sedum dasyphyllum | Thick-leaved Stonecrop | 44 | 2023 |
| plant | Sedum forsterianum | Rock Stonecrop | 34 | 2012 |
| plant | Sedum rupestre | Reflexed Stonecrop | 150 | 2023 |
| plant | Sedum sexangulare | Tasteless Stonecrop | 19 | 2010 |
| plant | Sedum spectabile | Butterfly Stonecrop | 11 | 2013 |
| plant | Sedum spurium | Caucasian-stonecrop | 38 | 2018 |
| plant | Sedum stoloniferum | Lesser Caucasian-stonecrop | 3 | 2003 |
| plant | Sedum telephium | Orpine | 30 | 2015 |
| plant | Sempervivum | a Sempervivum species (unidentified) | 1 | 2016 |
| plant | Sempervivum tectorum | House-leek | 6 | 2015 |
| plant | Senecio | a ragwort (unidentified) | 270 | 2023 |
| plant | Senecio cineraria x jacobaea = S. x albescens | a ragwort | 7 | 1998 |
| plant | Senecio inaequidens | Narrow-leaved Ragwort | 7 | 2023 |
| plant | Senecio jacobaea subsp. jacobaea | a Plant | 6 | 2020 |
| plant | Senecio jacobaea x aquaticus = S. x ostenfeldii | a ragwort | 1 | 1962 |
| plant | Senecio sarracenicus | Broad-leaved Ragwort | 31 | 2021 |
| plant | Senecio squalidus | Oxford Ragwort | 890 | 2023 |
| plant | Senecio squalidus x vulgaris = S. x baxteri | a Plant | 3 | 1944 |
| plant | Senecio sylvaticus | Heath Groundsel | 32 | 2007 |
| plant | Senecio viscosus | Sticky Groundsel | 69 | 2015 |
| plant | Senecio vulgaris | Groundsel | 3592 | 2023 |
| plant | Sequoiadendron giganteum | Wellingtonia | 91 | 2016 |
| plant | Sequoia or sequoiadendron sp. (unidentified redwood) | a redwood (unidentified) | 7 | 2016 |
| plant | Sequoia sempervirens | Coastal Redwood | 46 | 2015 |
| plant | Seriphidium maritimum | Sea Wormwood | 96 | 2016 |
| plant | Serratula | a Serratula species (unidentified) | 1 | 1999 |
| plant | Serratula tinctoria | Saw-wort | 275 | 2019 |
| plant | Setaria faberi | Nodding Bristle-grass | 3 | 1985 |
| plant | Setaria italica | Foxtail Bristle-grass | 8 | 1990 |
| plant | Setaria parviflora | Knotroot Bristle-grass | 2 | 1997 |
| plant | Setaria pumila | Yellow Bristle-grass | 23 | 2016 |
| plant | Setaria verticillata | Rough Bristle-grass | 11 | 2018 |
| plant | Setaria viridis | Green Bristle-grass | 51 | 2016 |
| plant | Setaria vulpiseta | a Plant | 1 | 1930 |
| plant | Sherardia arvensis | Field Madder | 726 | 2023 |
| plant | Sideritis montana | Mountain Ironwort | 1 | 1930 |
| plant | Silaum silaus | Pepper-saxifrage | 575 | 2021 |
| plant | Silene | a campion (unidentified) | 18 | 2023 |
| plant | Silene behen | a Plant | 1 | 1941 |
| plant | Silene conica | Sand Catchfly | 3 | 1994 |
| plant | Silene conoidea | a campion | 3 | 1947 |
| plant | Silene coronaria | Rose Campion | 13 | 2023 |
| plant | Silene dichotoma | Forked Catchfly | 4 | 1940 |
| plant | Silene dioica | Red Campion | 4302 | 2023 |
| plant | Silene flos-cuculi | Ragged Robin | 559 | 2022 |
| plant | Silene gallica | Small-flowered Catchfly | 8 | 2008 |
| plant | Silene latifolia | White Campion | 767 | 2021 |
| plant | Silene latifolia subsp. alba | a white campion | 4 | 2014 |
| plant | Silene latifolia x dioica = S. x hampeana | Hybrid Campion | 65 | 2012 |
| plant | Silene muscipula | a campion | 3 | 1939 |
| plant | Silene noctiflora | Night-flowering Catchfly | 21 | 2010 |
| plant | Silene stricta | a Plant | 1 | 1922 |
| plant | Silene uniflora | Sea Campion | 74 | 2019 |
| plant | Silene vulgaris | Bladder Campion | 158 | 2021 |
| plant | Silene vulgaris subsp. vulgaris | a bladder campion | 302 | 2016 |
| plant | Silybum marianum | Milk Thistle | 18 | 2018 |
| plant | Sinapis alba | White Mustard | 19 | 2016 |
| plant | Sinapis alba subsp. alba | a white mustard | 19 | 1997 |
| plant | Sinapis arvensis | Charlock | 1460 | 2023 |
| plant | Sison amomum | Stone Parsley | 707 | 2023 |
| plant | Sisymbrium | a Sisymbrium species (unidentified) | 1 | 1996 |
| plant | Sisymbrium altissimum | Tall Rocket | 7 | 1993 |
| plant | Sisymbrium erysimoides | French Rocket | 2 | 1939 |
| plant | Sisymbrium irio | London Rocket | 3 | 1958 |
| plant | Sisymbrium loeselii | False London Rocket | 3 | 1985 |
| plant | Sisymbrium officinale | Hedge Mustard | 2692 | 2023 |
| plant | Sisymbrium orientale | Eastern Rocket | 78 | 2023 |
| plant | Sisymbrium septulatum | a Plant | 2 | 1964 |
| plant | Sisymbrium volgense | Russian Mustard | 2 | 1947 |
| plant | Sisyrinchium striatum | Pale Yellow-eyed-grass | 7 | 2018 |
| plant | Sium latifolium | Greater Water-parsnip | 14 | 2016 |
| plant | Skimmia japonica | a Plant | 1 | 2013 |
| plant | Smyrnium | a Smyrnium species (unidentified) | 2 | 2023 |
| plant | Smyrnium olusatrum | Alexanders | 519 | 2023 |
| plant | Smyrnium perfoliatum | Perfoliate Alexanders | 1 | 2013 |
| plant | Solanum | a Solanum species (unidentified) | 2 | 2020 |
| plant | Solanum capsicastrum | Winter-cherry | 32 | 2000 |
| plant | Solanum crispum | Chilean Nightshade | 1 | 2015 |
| plant | Solanum diflorum | a Plant | 1 | 2000 |
| plant | Solanum dulcamara | Bittersweet | 3686 | 2023 |
| plant | Solanum dulcamara var. marinum | a bittersweet | 1 | 1999 |
| plant | Solanum laciniatum | Kangaroo-apple | 1 | 2019 |
| plant | Solanum nigrum | Black Nightshade | 495 | 2020 |
| plant | Solanum nigrum subsp. nigrum | a black nightshade | 4 | 2016 |
| plant | Solanum physalifolium | Green Nightshade | 4 | 2009 |
| plant | Solanum rostratum | Buffalo-bur | 3 | 2017 |
| plant | Solanum sisymbriifolium | Red Buffalo-bur | 3 | 1960 |
| plant | Solanum triflorum | Small Nightshade | 3 | 1930 |
| plant | Solanum tuberosum | Potato | 37 | 2020 |
| plant | Soleirolia soleirolii | Mind-your-own-business | 236 | 2023 |
| plant | Solidago | a goldenrod (unidentified) | 5 | 2007 |
| plant | Solidago canadensis | Canadian Goldenrod | 193 | 2019 |
| plant | Solidago gigantea | Early Goldenrod | 15 | 2017 |
| plant | Solidago rugosa | Rough-stemmed Goldenrod | 1 | 1988 |
| plant | Solidago virgaurea | Goldenrod | 197 | 2023 |
| plant | Sonchus | a sow-thistle (unidentified) | 80 | 2023 |
| plant | Sonchus arvensis | Perennial Sow-thistle | 1183 | 2021 |
| plant | Sonchus arvensis subsp. uliginosus | a perennial sow-thistle | 1 | 1984 |
| plant | Sonchus asper | Prickly Sow-thistle | 3536 | 2023 |
| plant | Sonchus oleraceus | Smooth Sow-thistle | 3411 | 2023 |
| plant | Sophora japonica | Scholars Tree | 1 | 2015 |
| plant | Sorbaria tomentosa | Himalayan Sorbaria | 3 | 1998 |
| plant | Sorbus | a whitebeam or a service-tree or other Sorbus (unidentified) | 13 | 2023 |
| plant | Sorbus anglica | English Whitebeam | 33 | 2018 |
| plant | Sorbus aria | Whitebeam | 331 | 2023 |
| plant | Sorbus aria agg. | Whitebeam agg. | 194 | 2014 |
| plant | Sorbus aria x torminalis = S. x tomentella | Wye Whitebeam | 2 | 1992 |
| plant | Sorbus aucuparia | Rowan | 628 | 2023 |
| plant | Sorbus aucuparia x aria = S. x thuringiaca | Oakleaf Mountain Ash | 34 | 2015 |
| plant | Sorbus bristoliensis | Bristol Whitebeam | 64 | 2023 |
| plant | Sorbus commixta | Japanese Rowan | 1 | 2006 |
| plant | Sorbus croceocarpa | Orange Whitebeam | 8 | 2015 |
| plant | Sorbus decipiens | Sharp-toothed Whitebeam | 12 | 2012 |
| plant | Sorbus domestica | Service-tree | 15 | 2014 |
| plant | Sorbus eminens | Round-leaved Whitebeam | 41 | 2016 |
| plant | Sorbus glabriscula | Hupeh Rowan | 5 | 2000 |
| plant | Sorbus hybrida | Swedish Service-tree | 2 | 2018 |
| plant | Sorbus intermedia | Swedish Whitebeam | 50 | 2018 |
| plant | Sorbus intermedia agg. | Swedish Whitebeam (agg.) | 49 | 2007 |
| plant | Sorbus 'Joseph Rock' | a whitebeam | 5 | 2000 |
| plant | Sorbus latifolia | Broad-leaved Whitebeam | 13 | 2023 |
| plant | Sorbus leighensis | a whitebeam | 2 | 2010 |
| plant | Sorbus porrigentiformis | Grey-leaved Whitebeam | 33 | 2009 |
| plant | Sorbus pseudofennica | Arran Service-tree | 2 | 2015 |
| plant | Sorbus rupicola | Rock Whitebeam | 1 | 1975 |
| plant | Sorbus sargentiana | Sargent's Rowan | 1 | 2000 |
| plant | Sorbus thibetica | Thibetan Whitebeam | 1 | 1999 |
| plant | Sorbus torminalis | Wild Service-tree | 214 | 2020 |
| plant | Sorbus vestita | Himalayan Whitebeam | 1 | 2000 |
| plant | Sorbus vilmorinii | Vilmorin's Rowan | 6 | 2000 |
| plant | Sorbus whiteana | White's Whitebeam (new species identified) | 15 | 2011 |
| plant | Sorbus (whitebeam) | a whitebeam (unidentified) | 40 | 2021 |
| plant | Sorbus wilmottiana | Wilmott's Whitebeam | 44 | 2019 |
| plant | Sorghum bicolor | Great Millet | 1 | 1933 |
| plant | Sorghum halepense | Johnson-grass | 17 | 2011 |
| plant | Sparaxis tricolor | Harlequin-flower | 1 | 2023 |
| plant | Sparganium | a bur-reed (unidentified) | 45 | 2013 |
| plant | Sparganium angustifolium | Floating Bur-reed | 2 | 2009 |
| plant | Sparganium emersum | Unbranched Bur-reed | 180 | 2016 |
| plant | Sparganium erectum | Branched Bur-reed | 1259 | 2020 |
| plant | Sparganium erectum subsp. erectum | a branched bur-reed | 7 | 2006 |
| plant | Sparganium erectum subsp. microcarpum | a branched bur-reed | 1 | 1921 |
| plant | Sparganium erectum subsp. neglectum | a branched bur-reed | 2 | 1936 |
| plant | Spartina | a Spartina species (unidentified) | 15 | 2017 |
| plant | Spartina anglica | Common Cord-grass | 241 | 2017 |
| plant | Spartina maritima x alterniflora = S. x townsendii | Townsend's Cord-grass | 16 | 2007 |
| plant | Spartium junceum | Spanish Broom | 3 | 2011 |
| plant | Spergula arvensis | Corn Spurrey | 68 | 2019 |
| plant | Spergularia | a Spergularia species (unidentified) | 6 | 2013 |
| plant | Spergularia marina | Lesser Sea-spurrey | 180 | 2019 |
| plant | Spergularia media | Greater Sea-spurrey | 209 | 2017 |
| plant | Spergularia purpurea | a Plant | 1 | 1931 |
| plant | Spergularia rubra | Sand Spurrey | 11 | 2012 |
| plant | Spergularia rupicola | Rock Sea-spurrey | 8 | 2006 |
| plant | Spiraea | a spiraea (unidentified) | 4 | 2018 |
| plant | Spiraea aggregate | a Plant | 1 | 2001 |
| plant | Spiraea canescens | Himalayan Spiraea | 6 | 2010 |
| plant | Spiraea cantoniensis x trilobata = S. x vanhouttei | Van Hotte's Spiraea | 1 | 2008 |
| plant | Spiraea multiflora x thunbergii = S. x arguta | Bridal-spray | 1 | 1992 |
| plant | Spiraea salicifolia | Bridewort | 3 | 2004 |
| plant | Spiranthes | a Spiranthes species (unidentified) | 2 | 2009 |
| plant | Spiranthes spiralis | Autumn Lady's-tresses | 209 | 2021 |
| plant | Spirodela polyrhiza | Greater Duckweed | 588 | 2018 |
| plant | Stachys | a woundwort (unidentified) | 23 | 2023 |
| plant | Stachys annua | Annual Yellow Woundwort | 3 | 1938 |
| plant | Stachys arvensis | Field Woundwort | 34 | 2019 |
| plant | Stachys byzantina | Lamb's-ear | 26 | 2020 |
| plant | Stachys germanica | Downy Woundwort | 1 | 1931 |
| plant | Stachys officinalis | Betony | 951 | 2023 |
| plant | Stachys officinalis var. officinalis | a Plant | 1 | 2000 |
| plant | Stachys palustris | Marsh Woundwort | 388 | 2020 |
| plant | Stachys sylvatica | Hedge Woundwort | 4584 | 2023 |
| plant | Stachys sylvatica x palustris = S. x ambigua | Hybrid Woundwort | 16 | 2018 |
| plant | Staphylea pinnata | Bladdernut | 2 | 1999 |
| plant | Stellaria | a stichwort (unidentified) | 31 | 2023 |
| plant | Stellaria alsine | Bog Stitchwort | 165 | 2023 |
| plant | Stellaria graminea | Lesser Stitchwort | 999 | 2021 |
| plant | Stellaria holostea | Greater Stitchwort | 1778 | 2023 |
| plant | Stellaria media | Common Chickweed | 3677 | 2023 |
| plant | Stellaria media agg. | Chickweed | 108 | 2022 |
| plant | Stellaria neglecta | Greater Chickweed | 319 | 2019 |
| plant | Stellaria nemorum | Wood Stitchwort | 1 | 2000 |
| plant | Stellaria pallida | Lesser Chickweed | 71 | 2014 |
| plant | Stellaria palustris | Marsh Stitchwort | 10 | 2008 |
| plant | Stratiotes aloides | Water-soldier | 10 | 2017 |
| plant | Suaeda maritima | Annual Sea-blite | 192 | 2017 |
| plant | Succisa | a Succisa species (unidentified) | 1 | 1999 |
| plant | Succisa pratensis | Devil's-bit Scabious | 981 | 2023 |
| plant | Sutera cordata | Ornamental Bacopa | 1 | 2010 |
| plant | Symphoricarpos | a Symphoricarpos species (unidentified) | 1 | 2016 |
| plant | Symphoricarpos albus | Snowberry | 1078 | 2023 |
| plant | Symphoricarpos microphyllus x orbiculatus = S. x chenaultii | Pink Snowberry | 2 | 2017 |
| plant | Symphoricarpos orbiculatus | a Plant | 7 | 2022 |
| plant | Symphoricarpos x doorenbosii | Amethyst or Coralberry | 1 | 1985 |
| plant | Symphytum | a comfrey (unidentified) | 88 | 2023 |
| plant | Symphytum asperum | Rough Comfrey | 8 | 2012 |
| plant | Symphytum bulbosum | Bulbous Comfrey | 1 | 2007 |
| plant | Symphytum caucasicum | Caucasian Comfrey | 9 | 2016 |
| plant | Symphytum grandiflorum | Creeping Comfrey | 24 | 2023 |
| plant | Symphytum officinale | Common Comfrey | 1169 | 2023 |
| plant | Symphytum officinale var. ochroleucum | a common comfrey | 1 | 1932 |
| plant | Symphytum officinale var. purpureum | a common comfrey | 1 | 2007 |
| plant | Symphytum officinale x asperum = S. x uplandicum | Russian Comfrey | 371 | 2023 |
| plant | Symphytum officinale x asperum x grandiflorum = S. 'Hidcote Blue' | Hidcote Comfrey | 18 | 2023 |
| plant | Symphytum officinale x asperum x tuberosum | a Plant | 3 | 2016 |
| plant | Symphytum orientale | White Comfrey | 49 | 2023 |
| plant | Symphytum tuberosum | Tuberous Comfrey | 23 | 2023 |
| plant | Syringa | a Syringa species (unidentified) | 2 | 2023 |
| plant | Syringa vulgaris | Lilac | 440 | 2023 |
| reptile | Serpentes | a Serpentes species (unidentified) | 1 | 2008 |
| reptile | Squamata | a snake or lizard (unidentified) | 3 | 2019 |
| sea-fan, sea anemone or jellyfish | Sagartia troglodytes | Cave-dwelling Anemone | 1 | 1938 |
| sea-fan, sea anemone or jellyfish | Sertularia argentea | a Sea-fan/Sea Anemone/Jellyfish | 1 | 1936 |
| sea-fan, sea anemone or jellyfish | Sertularia cupressina | a Sea-fan/Sea Anemone/Jellyfish | 5 | 1995 |
| sea-fan, sea anemone or jellyfish | Swiftia | a Swiftia species (unidentified) | 1 | 2021 |
| slime mould | Stemonitis | a Stemonitis species (unidentified) | 3 | 2012 |
| slime mould | Stemonitis flavogenita | a slime mould | 1 | 1999 |
| slime mould | Stemonitis fusca | a slime mould | 6 | 2020 |
| slime mould | Stemonitis fusca var. fusca | a slime mould | 6 | 2013 |
| slime mould | Stemonitis lignicola | a slime mould | 1 | 1997 |
| slime mould | Stemonitis nigrescens | a slime mould | 3 | 1982 |
| slime mould | Stemonitis smithii | a slime mould | 1 | 2000 |
| slime mould | Stemonitis virginiensis | a slime mould | 1 | 2005 |
| slime mould | Stemonitopsis hyperopta | a slime mould | 1 | 2008 |
| slime mould | Stemonitopsis typhina | a slime mould | 2 | 2008 |
| slime mould | Symphytocarpus flaccidus | a slime mould | 2 | 2017 |
| slime mould | Symphytocarpus trechisporus | a slime mould | 2 | 1997 |
| spider | Saaristoa abnormis | a money spider | 3 | 2003 |
| spider | Saaristoa firma | a money spider | 1 | 1996 |
| spider | Salticidae | a Salticidae species (unidentified) | 6 | 2022 |
| spider | Salticus | a Salticus species (unidentified) | 8 | 2020 |
| spider | Salticus cingulatus | a jumping spider | 1 | 2014 |
| spider | Salticus scenicus | a Zebra Spider | 96 | 2023 |
| spider | Sardinidion blackwalli | a comb-footed spider | 1 | 2023 |
| spider | Savignia frontata | a money spider | 16 | 2019 |
| spider | Scotophaeus blackwalli | Mouse Spider | 13 | 2020 |
| spider | Scytodes thoracica | Spitting Spider | 7 | 2018 |
| spider | Segestria | a Segestria species (unidentified) | 3 | 2023 |
| spider | Segestria bavarica | a six-eyed spider | 5 | 2014 |
| spider | Segestria florentina | Tube Web Spider | 76 | 2023 |
| spider | Segestria senoculata | Snake-back Spider | 28 | 2023 |
| spider | Silometopus ambiguus | a money spider | 2 | 2019 |
| spider | Simitidion simile | a comb-footed spider | 2 | 1965 |
| spider | Sitticus pubescens | a jumping spider | 1 | 2009 |
| spider | Sparassidae | a Sparassidae species (unidentified) | 2 | 2021 |
| spider | Steatoda | a false widow spider (unidentified) | 6 | 2023 |
| spider | Steatoda bipunctata | Rabbit Hutch Spider | 10 | 2017 |
| spider | Steatoda grossa | Cupboard Spider | 17 | 2023 |
| spider | Steatoda nobilis | Noble False Widow Spider | 26 | 2023 |
| spider | Stemonyphantes lineatus | a money spider | 7 | 2023 |
| springtail | Seira domestica | a springtail (Collembola) | 5 | 2019 |
| springtail | Symphypleona | a Symphypleona species (unidentified) | 1 | 2023 |
| stylops | Stylops | a Stylops species (unidentified) | 1 | 1978 |
| stylops | Stylops melittae | a stylop | 2 | 1978 |
| tick or mite (acarine) | Stenacis euonymi | a gall mite | 9 | 2022 |
| true fly - | Saltella sphondylii | a lesser dung fly | 8 | 2004 |
| true fly - | Sapromyza | a Sapromyza species (unidentified) | 1 | 1999 |
| true fly - | Sapromyza albiceps | a fly | 2 | 2001 |
| true fly - | Sapromyza basalis | a fly | 6 | 2020 |
| true fly - | Sapromyza hyalinata | a fly | 2 | 2020 |
| true fly - | Sapromyza opaca | a fly | 10 | 2009 |
| true fly - | Sapromyza quadricincta | a fly | 2 | 2018 |
| true fly - | Sapromyza quadripunctata | a fly | 14 | 2022 |
| true fly - | Sapromyza sexpunctata | a fly | 8 | 2013 |
| true fly - | Sarcophaga | a flesh fly (unidentified) | 39 | 2023 |
| true fly - | Sarcophaga carnaria | a flesh fly | 28 | 2021 |
| true fly - | Sarcophaga crassimargo | a flesh fly | 6 | 2006 |
| true fly - | Sarcophaga dissimilis | a flesh fly | 4 | 2013 |
| true fly - | Sarcophaga haemorrhoa | a flesh fly | 6 | 2002 |
| true fly - | Sarcophaga incisilobata | a flesh fly | 6 | 2003 |
| true fly - | Sarcophaga nigriventris | a flesh fly | 8 | 2009 |
| true fly - | Sarcophaga pumila | a flesh fly | 8 | 2013 |
| true fly - | Sarcophaga subvicina | a flesh fly | 2 | 2003 |
| true fly - | Sarcophaga vagans | a flesh fly | 3 | 2002 |
| true fly - | Sarcophaga villeneuvei | a flesh fly | 1 | 2003 |
| true fly - | Sarcophagidae | a Sarcophagidae species (unidentified) | 5 | 2023 |
| true fly - | Scaptomyza flava | a fruit fly | 4 | 2020 |
| true fly - | Scaptomyza graminum | a fruit fly | 5 | 2022 |
| true fly - | Scaptomyza griseola | a fruit fly | 1 | 2001 |
| true fly - | Scaptomyza pallida | a fruit fly | 30 | 2019 |
| true fly - | Scatella | a Scatella shore fly (unidentified) | 1 | 2007 |
| true fly - | Scatella lacustris | a shore fly | 23 | 2009 |
| true fly - | Scatella paludum | a shore fly | 9 | 2002 |
| true fly - | Scatella stagnalis | a shore fly | 22 | 2009 |
| true fly - | Scathophaga | a dung fly (unidentified) | 13 | 2023 |
| true fly - | Scathophaga calida | a dung fly | 1 | 2017 |
| true fly - | Scathophaga furcata | a dung fly | 17 | 2022 |
| true fly - | Scathophaga inquinata | a dung fly | 5 | 2009 |
| true fly - | Scathophaga litorea | a dung fly | 6 | 2009 |
| true fly - | Scathophaga lutaria | a dung fly | 2 | 2003 |
| true fly - | Scathophaga stercoraria | Yellow Dung Fly | 221 | 2023 |
| true fly - | Scathophaga suilla | a dung fly | 7 | 2012 |
| true fly - | Scathophagidae | a Scathophagidae species (unidentified) | 1 | 2017 |
| true fly - | Scatopse notata | a fly | 6 | 2017 |
| true fly - | Scatopsidae | a Scatopsidae species (unidentified) | 1 | 1997 |
| true fly - | Schoenomyza litorella | a muscid fly | 14 | 2009 |
| true fly - | Schwenckfeldina carbonaria | a fly | 13 | 2020 |
| true fly - | Sciara hemerobioides | a fly | 4 | 2022 |
| true fly - | Sciaridae | a Sciaridae species (unidentified) | 20 | 2008 |
| true fly - | Sciomyzidae | a Sciomyzidae species (unidentified) | 3 | 2015 |
| true fly - | Seioptera vibrans | a fly | 3 | 2014 |
| true fly - | Sepedon sphegea | a snail-killing fly | 7 | 2018 |
| true fly - | Sepedon spinipes | a snail-killing fly | 8 | 2001 |
| true fly - | Sepsidae | a Sepsidae species (unidentified) | 2 | 2021 |
| true fly - | Sepsis | a Sepsis species (unidentified) | 1 | 2017 |
| true fly - | Sepsis cynipsea | a lesser dung fly | 27 | 2022 |
| true fly - | Sepsis duplicata | a lesser dung fly | 4 | 2003 |
| true fly - | Sepsis flavimana | a lesser dung fly | 14 | 2013 |
| true fly - | Sepsis fulgens | a lesser dung fly | 47 | 2022 |
| true fly - | Sepsis orthocnemis | a lesser dung fly | 11 | 2022 |
| true fly - | Sepsis punctum | a lesser dung fly | 11 | 2009 |
| true fly - | Sepsis violacea | a lesser dung fly | 3 | 1998 |
| true fly - | Setacera | a Setacera species (unidentified) | 1 | 1997 |
| true fly - | Setacera micans | a shore fly | 1 | 2022 |
| true fly - | Sicus | a Sicus species (unidentified) | 1 | 2014 |
| true fly - | Silba fumosa | a fly | 15 | 2013 |
| true fly - | Simuliidae | a black fly (unidentified) | 45 | 2016 |
| true fly - | Simulium | a Simulium species (unidentified) | 1 | 2010 |
| true fly - | Simulium equinum | a black fly | 1 | 2002 |
| true fly - | Simulium ornatum complex | a black fly | 2 | 1997 |
| true fly - | Simulium variegatum | a black fly | 1 | 1998 |
| true fly - | Siphona | a Siphona species (unidentified) | 4 | 2023 |
| true fly - | Siphona geniculata | a parasitic fly | 23 | 2013 |
| true fly - | Siphonella oscinina | a fly | 1 | 1995 |
| true fly - | Solieria pacifica | a parasitic fly | 3 | 2013 |
| true fly - | Spanochaeta dorsalis | a muscid fly | 3 | 2001 |
| true fly - | Spelobia clunipes | a lesser dung fly | 1 | 1995 |
| true fly - | Spelobia parapusio | a lesser dung fly | 1 | 1996 |
| true fly - | Sphaerocera curvipes | a lesser dung fly | 1 | 2015 |
| true fly - | Sphaeroceridae | a Sphaeroceridae species (unidentified) | 3 | 2008 |
| true fly - | Spilogona marina | a muscid fly | 1 | 2000 |
| true fly - | Spiniphora dorsalis | a scuttle fly | 3 | 2020 |
| true fly - | Stearibia nigriceps | a fly | 1 | 2002 |
| true fly - | Stegana coleoptrata | a fruit fly | 2 | 2000 |
| true fly - | Stomorhina lunata | a blue bottle or green bottle | 1 | 2020 |
| true fly - | Stomoxys calcitrans | Stable Fly | 4 | 2022 |
| true fly - | Stratiomys | a Stratiomys soldier fly (unidentified) | 3 | 2019 |
| true fly - | Suillia affinis | a fly | 16 | 2022 |
| true fly - | Suillia atricornis | a fly | 6 | 2022 |
| true fly - | Suillia bicolor | a fly | 8 | 2020 |
| true fly - | Suillia dumicola | a fly | 1 | 1949 |
| true fly - | Suillia fuscicornis | a fly | 2 | 2003 |
| true fly - | Suillia humilis | a fly | 1 | 2000 |
| true fly - | Suillia notata | a fly | 3 | 2020 |
| true fly - | Suillia pallida | a fly | 8 | 2020 |
| true fly - | Suillia ustulata | a fly | 1 | 2000 |
| true fly - | Suillia variegata | a fly | 30 | 2023 |
| true fly - | Swammerdamella brevicornis | a fly | 3 | 2008 |
| true fly - | Sylvicola | a Sylvicola species (unidentified) | 8 | 2023 |
| true fly - | Sylvicola cinctus | a window gnat | 28 | 2022 |
| true fly - | Sylvicola fenestralis | a window gnat | 4 | 2006 |
| true fly - | Sylvicola punctatus | a window gnat | 35 | 2022 |
| true fly - | Syntormon | a Syntormon species (unidentified) | 1 | 2022 |
| true fly - cranefly | Symplecta hybrida | a cranefly | 1 | 1999 |
| true fly - cranefly | Symplecta pilipes | a cranefly | 3 | 2004 |
| true fly - cranefly | Symplecta stictica | a cranefly | 17 | 2009 |
| true fly - (diptera) | Sarcophaga anaces | an insect - true fly (Diptera) | 1 | 2013 |
| true fly - (diptera) | Sarcophaga depressifrons | an insect - true fly (Diptera) | 2 | 2006 |
| true fly - (diptera) | Sarcophaga melanura | an insect - true fly (Diptera) | 2 | 2008 |
| true fly - (diptera) | Sarcophaga rosellei | an insect - true fly (Diptera) | 1 | 2002 |
| true fly - (diptera) | Sarcophaga sexpunctata | an insect - true fly (Diptera) | 1 | 2003 |
| true fly - (diptera) | Sarcophaga sinuata | an insect - true fly (Diptera) | 5 | 2013 |
| true fly - (diptera) | Sarcophaga teretirostris | an insect - true fly (Diptera) | 4 | 2003 |
| true fly - (diptera) | Sarcophaga variegata | an insect - true fly (Diptera) | 3 | 2017 |
| true fly - (diptera) | Scatopsciara atomaria | a fly | 1 | 2001 |
| true fly - (diptera) | Sceptonia cryptocauda | an insect - true fly (Diptera) | 3 | 2006 |
| true fly - (diptera) | Scoliocentra confusa | an insect - true fly (Diptera) | 1 | 2000 |
| true fly - (diptera) | Sphaerophoria interrupta | an insect - true fly (Diptera) | 16 | 2021 |
| true fly - (diptera) | Stigmatomeria crassicornis | a fungus gnat | 5 | 2020 |
| true fly - (diptera) | Stiphrosoma cingulatum | an insect - true fly (Diptera) | 1 | 2009 |
| true fly - (diptera) | Sturmia bella | an insect - true fly (Diptera) | 1 | 2003 |
| true fly - fly | Solva marginata | a fly | 5 | 2004 |
| true fly - hoverfly | Scaeva pyrastri | a hoverfly | 104 | 2022 |
| true fly - hoverfly | Scaeva selenitica | a hoverfly | 6 | 2023 |
| true fly - hoverfly | Sericomyia silentis | a hoverfly | 12 | 2021 |
| true fly - hoverfly | Sericomyia superbiens | a hoverfly | 2 | 2001 |
| true fly - hoverfly | Sphaerophoria | a Sphaerophoria hoverfly (unidentified) | 59 | 2023 |
| true fly - hoverfly | Sphaerophoria fatarum | a hoverfly | 1 | 1999 |
| true fly - hoverfly | Sphaerophoria menthastri | a hoverfly | 12 | 2002 |
| true fly - hoverfly | Sphaerophoria rueppellii | a hoverfly | 5 | 2018 |
| true fly - hoverfly | Sphaerophoria scripta | a hoverfly | 269 | 2023 |
| true fly - hoverfly | Sphaerophoria species B | a hoverfly | 1 | 2017 |
| true fly - hoverfly | Sphaerophoria taeniata | a hoverfly | 4 | 2021 |
| true fly - hoverfly | Sphegina clunipes | a hoverfly | 10 | 2008 |
| true fly - hoverfly | Sphegina elegans | a hoverfly | 2 | 2003 |
| true fly - hoverfly | Sphegina verecunda | a hoverfly | 2 | 1999 |
| true fly - hoverfly | Syritta pipiens | a hoverfly | 266 | 2023 |
| true fly - hoverfly | Syrphidae | a hoverfly (unidentified) | 175 | 2023 |
| true fly - hoverfly | Syrphus | a Syrphus hoverfly (unidentified) | 97 | 2023 |
| true fly - hoverfly | Syrphus ribesii | a hoverfly | 215 | 2023 |
| true fly - hoverfly | Syrphus torvus | a hoverfly | 30 | 2022 |
| true fly - hoverfly | Syrphus vitripennis | a hoverfly | 135 | 2023 |
| true fly - midge, gnat or mosquito | Saigusaia flaviventris | a fungus gnat | 11 | 2020 |
| true fly - midge, gnat or mosquito | Sceptonia fumipes | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Sciophila fenestella | a fungus gnat | 2 | 2003 |
| true fly - midge, gnat or mosquito | Sciophila hirta | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Semudobia betulae | a gall midge | 1 | 1999 |
| true fly - midge, gnat or mosquito | Serromyia femorata | a biting midge | 2 | 1997 |
| true fly - midge, gnat or mosquito | Smittia aterrima | a non-biting midge | 2 | 1983 |
| true fly - midge, gnat or mosquito | Smittia pratorum | a non-biting midge | 3 | 1983 |
| true fly - midge, gnat or mosquito | Symmerus annulatus | a fungus gnat | 4 | 2001 |
| true fly - midge, gnat or mosquito | Synapha vitripennis | a fungus gnat | 5 | 2020 |
| true fly - midge, gnat or mosquito | Synendotendipes impar | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Synplasta gracilis | a fungus gnat | 3 | 2020 |
| true fly - midge, gnat or mosquito | Syntemna hungarica | a fungus gnat | 1 | 2000 |
| true fly - picture-winged, conopid or stilt-legged fly | Sicus ferrugineus | a fly | 62 | 2023 |
| true fly - picture-winged, conopid or stilt-legged fly | Sphenella marginata | a gall fly | 17 | 2023 |
| true fly - picture-winged, conopid or stilt-legged fly | Stemonocera cornuta | a gall fly | 1 | 2016 |
| true fly - robber, empid or dolichopid fly | Scellus notatus | a dolichopodid fly | 4 | 2009 |
| true fly - robber, empid or dolichopid fly | Scenopinus fenestralis | a window fly | 1 | 1995 |
| true fly - robber, empid or dolichopid fly | Scenopinus niger | a window fly | 2 | 2020 |
| true fly - robber, empid or dolichopid fly | Sciapus platypterus | a dolichopodid fly | 18 | 2020 |
| true fly - robber, empid or dolichopid fly | Sybistroma obscurellum | a dolichopodid fly | 14 | 2022 |
| true fly - robber, empid or dolichopid fly | Sympycnus pulicarius | a dolichopodid fly | 21 | 2022 |
| true fly - robber, empid or dolichopid fly | Sympycnus spiculatus | a dolichopodid fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Syntormon bicolorellum | a dolichopodid fly | 4 | 2009 |
| true fly - robber, empid or dolichopid fly | Syntormon denticulatum | a dolichopodid fly | 9 | 2003 |
| true fly - robber, empid or dolichopid fly | Syntormon macula | a dolichopodid fly | 1 | 1952 |
| true fly - robber, empid or dolichopid fly | Syntormon pallipes | a dolichopodid fly | 30 | 2009 |
| true fly - robber, empid or dolichopid fly | Syntormon pumilus | a dolichopodid fly | 8 | 2009 |
| true fly - robber, empid or dolichopid fly | Syntormon zelleri | a dolichopodid fly | 1 | 1987 |
| true fly - robber, empid or dolichopid fly | Systenus pallipes | a dolichopodid fly | 1 | 1948 |
| true fly - robber, empid or dolichopid fly | Systenus scholtzii | a dolichopodid fly | 1 | 2000 |
| true fly - soldier or snipe fly | Sargus bipunctatus | Twin-spot Centurion | 18 | 2022 |
| true fly - soldier or snipe fly | Sargus flavipes | Yellow-legged Centurion | 4 | 2022 |
| true fly - soldier or snipe fly | Sargus iridatus | Iridescent Centurion | 10 | 2021 |
| true fly - soldier or snipe fly | Stratiomyidae | a Stratiomyidae soldier fly (unidentified) | 21 | 2016 |
| true fly - soldier or snipe fly | Stratiomys potamida | Banded General | 16 | 2021 |
| true fly - soldier or snipe fly | Stratiomys singularior | Flecked General | 17 | 2021 |
| true fly - soldier or snipe fly | Symphoromyia immaculata | a snipe fly | 1 | 2000 |
| worm | Sabellaria | a Sabellaria species (unidentified) | 1 | 1939 |
| worm | Sabellaria alveolata | Honeycomb Worm | 18 | 2019 |
| worm | Satchellius mammalis | Little Tree Worm | 8 | 2017 |
| worm | Scoloplos (Scoloplos) armiger | an annelid | 4 | 1995 |
| worm | Spirobranchus triqueter | an annelid | 2 | 1972 |