Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| algae or stonewort | Tolypella glomerata | Clustered stonewort | 3 | 1990 |
| algae or stonewort | Tolypella intricata | Tassel stonewort | 12 | 2014 |
| algae or stonewort | Tolypella salina | a stonewort | 1 | 1922 |
| algae or stonewort | Trentepohlia | a Trentepohlia species (unidentified) | 3 | 2013 |
| algae or stonewort | Trentepohlia aurea | an alga | 3 | 2023 |
| amphibian | Triturus | Newt | 24 | 2023 |
| amphibian | Triturus cristatus | Great Crested Newt | 1996 | 2025 |
| amphibian | Triturus or Lissotriton | a newt (unidentified) | 1048 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tachysphex pompiliformis | a solitary wasp | 3 | 2010 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Temnothorax nylanderi | an ant | 6 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredinidae | a Tenthredinidae species (unidentified) | 3 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredininae | a Tenthredininae species (unidentified) | 1 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo | a Tenthredo species (unidentified) | 2 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo arcuata | Clover Sawfly | 17 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo arcuata/brevicornis/notha/schaefferi agg. | Complex Tenthredo arcuata | 2 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo atra | Dark Sawfly | 1 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo brevicornis | Trefoil Sawfly | 1 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo colon s.l. | Colon Sawfly | 1 | 2015 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo livida | Livid Sawfly | 4 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo maculata | Greater Girdled Sawfly | 4 | 2015 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo mesomela | Common Green Sawfly | 14 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo notha | Broadbar Clover Sawfly | 2 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo omissa | Fen Sawfly | 2 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredopsis | a Tenthredopsis species (unidentified) | 2 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredopsis coquebertii | Coqueberts Sawfly | 1 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredopsis litterata | Inscribed Sawfly | 1 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredopsis nassata | Uninscribed Sawfly | 6 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredopsis ornata | Ornate Sawfly | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo scrophulariae | Figwort Sawfly | 58 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo temula | Wayward Sawfly | 10 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo thompsoni | Thompsons Sawfly | 3 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tenthredo zona | Zonal Sawfly | 2 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tetrastichus | a Tetrastichus wasp (unidentified) | 1 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Theocolax formiciformis | a chalcid wasp | 1 | 1969 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tiphia femorata | a solitary wasp | 4 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tiphia minuta | Small Tiphia | 14 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus | a Diomorus species (unidentified) | 1 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus affinis | a chalcid wasp | 70 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus auratus | a chalcid wasp | 46 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus bedeguaris | a chalcid wasp | 6 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus chloromerus | a chalcid wasp | 1 | 1995 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus flavipes | a chalcid wasp | 59 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus geranii | a chalcid wasp | 12 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Torymus geranii/auratus | an insect - hymenopteran | 8 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tranosema rostrale | an insect - hymenopteran | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tranosemella praerogator | an insect - hymenopteran | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Triaspis pallipes | a braconid wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichiosoma | Hairy-clubhorn Sawflies | 2 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichiosoma tibiale | Yellow-legged Hairy-clubhorn | 2 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichomalopsis potatoriae | a chalcid wasp | 1 | 1995 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichomalus posticus | a chalcid wasp | 1 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichopria aequata | a small parasitic wasp | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichopria verticillata | a small parasitic wasp | 2 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trichrysis cyanea | a rubytail wasp | 9 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tromatobia lineatoria | an ichneumon wasp | 6 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trybliographa rapae | a small parasitic wasp | 5 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trybliographa scotica | a small parasitic wasp | 2 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trychosis legator | an insect - hymenopteran | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trypoxylon attenuatum | Slender Wood Borer Wasp | 19 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trypoxylon clavicerum | Club Horned Wood Borer Wasp | 3 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Trypoxylon figulus | Black Wood Borer Wasp | 9 | 2005 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Tycherus elongatus | an ichneumon wasp | 1 | 2002 |
| bacterium | Tolypothrix | a Tolypthrix blue-green algae (unidentified) | 1 | 1998 |
| beetle | Tachinus | a Tachinus species (unidentified) | 1 | 2018 |
| beetle | Tachinus laticollis | a rove beetle | 6 | 2022 |
| beetle | Tachinus pallipes | a rove beetle | 2 | 2020 |
| beetle | Tachinus rufipes | a rove beetle | 81 | 2023 |
| beetle | Tachinus subterraneus | a rove beetle | 12 | 2021 |
| beetle | Tachyerges salicis | a weevil | 7 | 2015 |
| beetle | Tachyerges stigma | a weevil | 2 | 1985 |
| beetle | Tachyporus | a Tachyporus rove beetle (unidentified) | 9 | 2023 |
| beetle | Tachyporus chrysomelinus | a rove beetle | 34 | 2023 |
| beetle | Tachyporus chrysomelinus/dispar agg. | a rove beetle | 1 | 1969 |
| beetle | Tachyporus dispar | a rove beetle | 47 | 2023 |
| beetle | Tachyporus formosus | a rove beetle | 4 | 2020 |
| beetle | Tachyporus hypnorum | a rove beetle | 169 | 2024 |
| beetle | Tachyporus nitidulus | a rove beetle | 14 | 2023 |
| beetle | Tachyporus obtusus | a rove beetle | 27 | 2023 |
| beetle | Tachyporus pallidus | a rove beetle | 4 | 2018 |
| beetle | Tachyporus solutus | a rove beetle | 16 | 2022 |
| beetle | Tachyporus tersus | a rove beetle | 1 | 2008 |
| beetle | Tachyura parvula | a ground beetle | 2 | 2014 |
| beetle | Taeniapion urticarium | a seed weevil | 10 | 2015 |
| beetle | Tanysphyrus lemnae | Duckweed Weevil | 31 | 2007 |
| beetle | Taphrorychus bicolor | a bark or ambrosia beetle | 1 | 2016 |
| beetle | Tasgius ater | a rove beetle | 6 | 2017 |
| beetle | Tasgius globulifer | a rove beetle | 4 | 2020 |
| beetle | Tasgius melanarius | a rove beetle | 2 | 2014 |
| beetle | Tasgius morsitans | a rove beetle | 14 | 2020 |
| beetle | Tatianaerhynchites aequatus | Apple Fruit Rhynchites | 37 | 2024 |
| beetle | Telmatophilus caricis | a silken fungus beetle | 1 | 2014 |
| beetle | Telmatophilus typhae | a silken fungus beetle | 1 | 2001 |
| beetle | Temnocerus nanus | a leafroller weevil | 1 | 2019 |
| beetle | Tenebrio | Indet. Mealworm Beetle | 1 | 2013 |
| beetle | Tenebrio molitor | Mealworm Beetle | 9 | 2022 |
| beetle | Tetartopeus quadratus | a rove beetle | 1 | 2004 |
| beetle | Tetratoma ancora | a shiny fungus beetle | 1 | 2020 |
| beetle | Tetratoma desmarestii | a shiny fungus beetle | 1 | 2016 |
| beetle | Tetratoma fungorum | a shiny fungus beetle | 1 | 2001 |
| beetle | Tetropium gabrieli | Larch Longhorn | 1 | 2017 |
| beetle | Tetrops praeustus | Plum Beetle | 14 | 2022 |
| beetle | Teuchestes fossor | a dung beetle or chafer | 5 | 2023 |
| beetle | Thamiaraea cinnamomea | a rove beetle | 1 | 2001 |
| beetle | Thanasimus formicarius | Ant Beetle | 2 | 2006 |
| beetle | Thanatophilus sinuatus | a sexton beetle | 3 | 2025 |
| beetle | Thryogenes festucae | a weevil | 2 | 2000 |
| beetle | Thryogenes nereis | a weevil | 12 | 2009 |
| beetle | Tillus elongatus | a chequered beetle | 19 | 2023 |
| beetle | Timarcha goettingensis | Small Bloody-nosed Beetle | 18 | 2023 |
| beetle | Timarcha tenebricosa | Bloody-nosed Beetle | 51 | 2021 |
| beetle | Tournotaris bimaculata | a weevil | 2 | 2015 |
| beetle | Trachodes hispidus | a weevil | 2 | 1979 |
| beetle | Trachyphloeus | a Trachyphloeus species (unidentified) | 2 | 2013 |
| beetle | Trachyphloeus alternans | a weevil | 3 | 1968 |
| beetle | Trachys compressus | a jewel beetle | 4 | 2019 |
| beetle | Trachys troglodytes | Devil's-bit Jewel Beetle | 2 | 2004 |
| beetle | Trechoblemus micros | a ground beetle | 8 | 1999 |
| beetle | Trechus obtusus | a ground beetle | 17 | 2023 |
| beetle | Trechus quadristriatus | a ground beetle | 68 | 2020 |
| beetle | Trechus rubens | a ground beetle | 1 | 2014 |
| beetle | Tribolium castaneum | Rust-red Flour Beetle | 3 | 2013 |
| beetle | Trichius fasciatus | Bee Beetle | 1 | 1979 |
| beetle | Trichosirocalus troglodytes | a weevil | 85 | 2021 |
| beetle | Triplax aenea | a shiny fungus beetle | 4 | 2021 |
| beetle | Triplax russica | a shiny fungus beetle | 5 | 2023 |
| beetle | Trixagus carinifrons | a small false click beetle | 3 | 2023 |
| beetle | Trixagus dermestoides | a small false click beetle | 10 | 2021 |
| beetle | Trixagus obtusus | a small false click beetle | 7 | 2019 |
| beetle | Tropiphorus elevatus | a weevil | 2 | 2009 |
| beetle | Trox scaber | a hide beetle | 3 | 2020 |
| beetle | Trypodendron | a Trypodendron species (unidentified) | 1 | 1964 |
| beetle | Trypodendron domesticum | a bark or ambrosia beetle | 3 | 2021 |
| beetle | Tychius junceus | a weevil | 2 | 1968 |
| beetle | Tychius meliloti | a weevil | 4 | 2014 |
| beetle | Tychius picirostris | a weevil | 15 | 2017 |
| beetle | Tychius squamulatus | a weevil | 4 | 2018 |
| beetle | Tychius stephensi | a weevil | 1 | 2007 |
| beetle | Tychus niger | a short-winged mould beetle | 5 | 2018 |
| beetle | Typhaea stercorea | Hairy Fungus Beetle | 1 | 1971 |
| beetle | Typhaeus typhoeus | Minotaur Beetle | 5 | 2022 |
| beetle | Tytthaspis sedecimpunctata | 16-spot Ladybird | 120 | 2025 |
| bird | Tachybaptus ruficollis | Little Grebe | 11508 | 2024 |
| bird | Tachymarptis melba | Alpine Swift | 5 | 2002 |
| bird | Tadorna | a Tadorna species (unidentified) | 1 | 2012 |
| bird | Tadorna ferruginea | Ruddy Shelduck | 101 | 2010 |
| bird | Tadorna tadorna | Shelduck | 17870 | 2025 |
| bird | Taeniopygia guttata | Zebra Finch | 2 | 2018 |
| bird | Tarsiger cyanurus | Red-flanked Bluetail | 62 | 2014 |
| bird | Tauraco leucotis | White-cheeked Turaco | 1 | 2013 |
| bird | Thalasseus sandvicensis | Sandwich Tern | 213 | 2022 |
| bird | Trachyphonus erythrocephalus | Red-and-yellow Barbet | 1 | 2016 |
| bird | Tringa erythropus | Spotted Redshank | 1095 | 2022 |
| bird | Tringa flavipes | Lesser Yellowlegs | 107 | 2020 |
| bird | Tringa glareola | Wood Sandpiper | 988 | 2022 |
| bird | Tringa nebularia | Greenshank | 3085 | 2025 |
| bird | Tringa ochropus | Green Sandpiper | 6317 | 2022 |
| bird | Tringa stagnatilis | Marsh Sandpiper | 1 | 1986 |
| bird | Tringa totanus | Redshank (bird) | 13985 | 2025 |
| bird | Troglodytes troglodytes | Wren | 45026 | 2025 |
| bird | Troglodytidae | Wrens | 5 | 2024 |
| bird | Turdus | Thrush Species | 122 | 2017 |
| bird | Turdus iliacus | Redwing | 16123 | 2025 |
| bird | Turdus merula | Blackbird | 75047 | 2025 |
| bird | Turdus philomelos | Song Thrush | 28052 | 2025 |
| bird | Turdus pilaris | Fieldfare | 9654 | 2025 |
| bird | Turdus pilaris/iliacus | Redwing/Fieldfare | 6 | 2010 |
| bird | Turdus ruficollis | Black-throated Thrush | 1 | 1996 |
| bird | Turdus torquatus | Ring Ouzel | 564 | 2022 |
| bird | Turdus viscivorus | Mistle Thrush | 9116 | 2025 |
| bird | Turdus viscivorus/philomelos | Mistle/Song Thrush | 4 | 2005 |
| bird | Tyto alba | Barn Owl | 3736 | 2025 |
| booklouse or barklouse | Trichadenotecnum sexpunctatum | a booklouse or barklouse | 1 | 2002 |
| booklouse or barklouse | Trichopsocus brincki | an insect - booklouse (Psocoptera) | 2 | 2015 |
| booklouse or barklouse | Trichopsocus clarus | a booklouse or barklouse | 2 | 2008 |
| bristletail (silverfish and allies) | Thermobia domestica | Fire-brat | 1 | 1976 |
| bryozoan | Tegella | a Tegella species (unidentified) | 1 | 1941 |
| bug | Tachycixius | a Tachycixius species (unidentified) | 1 | 2019 |
| bug | Tachycixius pilosus | a lacehopper | 15 | 2024 |
| bug | Taphropeltus contractus | a ground bug | 3 | 2023 |
| bug | Temnostethus (Montandoniella) gracilis | a flower bug or bloodsucking bug | 4 | 2023 |
| bug | Temnostethus (Montandoniella) pusillus | a flower bug or bloodsucking bug | 1 | 2020 |
| bug | Teratocoris | a Teratocoris species (unidentified) | 1 | 2015 |
| bug | Teratocoris antennatus | a plantbug or grassbug | 3 | 2004 |
| bug | Teratocoris saundersi | a plantbug or grassbug | 3 | 2020 |
| bug | Tetraneura (Tetraneura) ulmi | Fig Gall | 3 | 2022 |
| bug | Thamnotettix dilutior | a leafhopper | 9 | 2022 |
| bug | Thyreocoris scarabaeoides | Negro Bug | 2 | 2006 |
| bug | Tingis | a Tingis species (unidentified) | 1 | 2016 |
| bug | Tingis (Tingis) ampliata | Creeping Thistle Lacebug | 32 | 2023 |
| bug | Tingis (Tingis) cardui | Spear Thistle Lacebug | 33 | 2024 |
| bug | Tinicephalus (Tinicephalus) hortulanus | a plantbug or grassbug | 1 | 2024 |
| bug | Trama (Trama) rara | an aphid | 1 | 2023 |
| bug | Trama (Trama) troglodytes | an aphid | 1 | 2015 |
| bug | Trapezonotus | a Trapezonotus species (unidentified) | 1 | 2021 |
| bug | Trapezonotus (Trapezonotus) arenarius | a ground bug | 4 | 2019 |
| bug | Tremulicerus distinguendus | a leafhopper | 1 | 2018 |
| bug | Tremulicerus tremulae | a leafhopper | 1 | 2013 |
| bug | Tremulicerus vitreus | a leafhopper | 2 | 2023 |
| bug | Trigonotylus caelestialium | a plantbug or grassbug | 5 | 2022 |
| bug | Trigonotylus ruficornis | a plantbug or grassbug | 1 | 2018 |
| bug | Trioza | a Trioza species (unidentified) | 2 | 2008 |
| bug | Trioza alacris | Bay Sucker | 1 | 2014 |
| bug | Trioza centranthi | a jumping plantlouse | 12 | 2023 |
| bug | Trioza urticae | a jumping plantlouse | 6 | 2019 |
| bug | Tritomegas bicolor | Pied Shieldbug | 17 | 2024 |
| bug | Troilus luridus | Bronze Shieldbug | 25 | 2025 |
| bug | Tuberculatus (Tuberculoides) annulatus | an aphid | 1 | 2015 |
| bug | Tuberolachnus (Tuberolachnus) salignus | Large Willow Aphid | 4 | 2020 |
| bug | Tupiocoris rhododendri | a plantbug or grassbug | 1 | 2016 |
| bug | Tuponia (Chlorotuponia) brevirostris | a plantbug or grassbug | 1 | 2020 |
| bug | Turrutus socialis | a leafhopper | 1 | 2019 |
| bug | Typhlocyba quercus | a leafhopper | 2 | 2023 |
| caddis fly | Tinodes | a Tinodes species (unidentified) | 1 | 2023 |
| caddis fly | Tinodes unicolor | a caddisfly | 1 | 2018 |
| caddis fly | Tinodes waeneri | a caddisfly | 4 | 2024 |
| caddis fly | Triaenodes bicolor | a caddisfly | 27 | 2013 |
| caddis fly | Trichoptera | caddisflies | 101 | 2023 |
| crustacean | Talitrus saltator | a sand hopper | 7 | 2023 |
| crustacean | Tigriopus brevicornis | a crustacean | 2 | 1973 |
| crustacean | Trichoniscidae | a Trichoniscidae species (unidentified) | 1 | 2023 |
| crustacean | Trichoniscus pusillus agg. | a woodlouse | 2 | 2015 |
| fish | Taurulus bubalis | Sea Scorpion | 1 | 1933 |
| fish | Thunnus thynnus | Blue-fin tuna | 1 | 2016 |
| fish | Thymallus thymallus | Grayling (fish) | 4 | 2003 |
| fish | Tinca tinca | Tench | 15 | 2018 |
| fish | Trachinus draco | Greater Weever | 1 | 1933 |
| fish | Trachurus trachurus | Horse Mackerel | 3 | 1999 |
| fish | Trigla lyra | Piper | 1 | 1879 |
| fish | Trisopterus esmarkii | Norway Pout | 1 | 1999 |
| fish | Trisopterus luscus | Pouting | 4 | 1999 |
| fish | Trisopterus minutus | Poor Cod | 4 | 2018 |
| fungus | Taphrina alni | Alder Tongue | 6 | 2022 |
| fungus | Taphrina betulina | Birch Besom | 2 | 2014 |
| fungus | Taphrina padi | Bird Cherry Pocket | 8 | 2017 |
| fungus | Taphrina populina | an ascomycete fungus | 1 | 2023 |
| fungus | Taphrina pruni | Pocket Plum | 6 | 2023 |
| fungus | Taphrina ulmi | an ascomycete fungus | 2 | 1997 |
| fungus | Tarzetta catinus | Greater Toothed Cup | 6 | 2010 |
| fungus | Tarzetta cupularis | Toothed Cup | 6 | 2011 |
| fungus | Tatraea dumbirensis | Beechwood Goblet | 1 | 1995 |
| fungus | Tephrocybe baeosperma | a basidiomycete fungus | 4 | 1992 |
| fungus | Tephrocybe confusa | a basidiomycete fungus | 2 | 1990 |
| fungus | Tephrocybe impexa | a fungus | 6 | 2006 |
| fungus | Tephrocybe platypus | a fungus | 1 | 2004 |
| fungus | Tephrocybe rancida | Rancid Greyling | 2 | 1996 |
| fungus | Terana coerulea | Cobalt Crust | 50 | 2023 |
| fungus | Thekopsora agrimoniae | Agrimony Rust | 3 | 2023 |
| fungus | Thelephora anthocephala | a coral fungus | 3 | 2023 |
| fungus | Thelephora caryophyllea | Carnation Earthfan | 1 | 2014 |
| fungus | Thelephora palmata | Stinking Earthfan | 4 | 2021 |
| fungus | Thelephora penicillata | Urchin Earthfan | 1 | 2000 |
| fungus | Thelephora terrestris | Earth-fan | 4 | 2012 |
| fungus | Thelonectria veuillotiana | an ascomycete fungus | 4 | 2014 |
| fungus | Tomentella badia | a basidiomycete fungus | 2 | 2008 |
| fungus | Tomentella crinalis | a basidiomycete fungus | 2 | 2008 |
| fungus | Tomentella sublilacina | a basidiomycete fungus | 1 | 2008 |
| fungus | Torula herbarum | a fungus | 1 | 2010 |
| fungus | Trametes | a Trametes species (unidentified) | 6 | 2023 |
| fungus | Trametes betulina | Birch Mazegill | 11 | 2019 |
| fungus | Trametes gibbosa | Lumpy Bracket | 98 | 2018 |
| fungus | Trametes hirsuta | Hairy Bracket | 18 | 2020 |
| fungus | Trametes ochracea | Ochre Bracket | 6 | 2023 |
| fungus | Trametes pubescens | a basidiomycete fungus | 8 | 2013 |
| fungus | Trametes suaveolens | Fragrant Bracket | 1 | 2004 |
| fungus | Trametes versicolor | Turkey Tail fungus | 649 | 2024 |
| fungus | Tranzschelia | a Tranzschelia species (unidentified) | 1 | 2023 |
| fungus | Tranzschelia anemones | a rust | 1 | 2023 |
| fungus | Tranzschelia discolor | Plum Rust | 2 | 2008 |
| fungus | Tranzschelia pruni-spinosae | Blackthorn Rust | 1 | 2008 |
| fungus | Trechispora cohaerens | a basidiomycete fungus | 1 | 2008 |
| fungus | Trechispora farinacea | a basidiomycete fungus | 9 | 2005 |
| fungus | Trechispora laevis | a fungus | 2 | 2008 |
| fungus | Trechispora mollusca | a basidiomycete fungus | 1 | 2013 |
| fungus | Trechispora nivea | a basidiomycete fungus | 1 | 2000 |
| fungus | Trechispora stellulata | a fungus | 1 | 2008 |
| fungus | Tremella encephala | Conifer Brain | 1 | 2002 |
| fungus | Tremella globispora | a basidiomycete fungus | 5 | 2000 |
| fungus | Tremella mesenterica | Golden Jelly Fungus | 160 | 2025 |
| fungus | Trichaptum abietinum | Purplepore Bracket | 25 | 2023 |
| fungus | Trichoderma aureoviride | a fungus | 1 | 2020 |
| fungus | Trichoderma citrinoviride | an ascomycete fungus | 1 | 1970 |
| fungus | Trichoderma pulvinatum | Ochre Cushion | 6 | 2005 |
| fungus | Trichoderma viride | an ascomycete fungus | 2 | 2014 |
| fungus | Trichoglossum hirsutum | Hairy Earthtongue | 9 | 2020 |
| fungus | Trichoglossum hirsutum var. hirsutum | an ascomycete fungus | 8 | 2000 |
| fungus | Tricholoma | a Tricholoma basidiomycete fungus (unidentified) | 3 | 2023 |
| fungus | Tricholoma acerbum | Bitter Knight | 2 | 1998 |
| fungus | Tricholoma albobrunneum | a basidiomycete fungus | 5 | 2010 |
| fungus | Tricholoma album | White Knight | 56 | 2020 |
| fungus | Tricholoma argyraceum | a basidiomycete fungus | 27 | 2014 |
| fungus | Tricholoma atrosquamosum var. atrosquamosum | Dark Scaled Knight | 10 | 2010 |
| fungus | Tricholoma atrosquamosum var. squarrulosum | a basidiomycete fungus | 1 | 1997 |
| fungus | Tricholoma basirubens | a fungus | 4 | 2007 |
| fungus | Tricholoma batschii | a fungus | 1 | 2005 |
| fungus | Tricholoma cingulatum | Girdled Knight | 3 | 2023 |
| fungus | Tricholoma columbetta | Blue Spot Knight | 2 | 2008 |
| fungus | Tricholoma fulvum | Birch Knight | 16 | 2012 |
| fungus | Tricholoma hemisulphureum nom. inval. | a fungus | 19 | 2008 |
| fungus | Tricholoma imbricatum | Matt Knight | 14 | 2014 |
| fungus | Tricholoma inocybeoides | a basidiomycete fungus | 1 | 2006 |
| fungus | Tricholoma lascivum | Aromatic Knight | 45 | 2021 |
| fungus | Tricholoma orirubens | a basidiomycete fungus | 7 | 2014 |
| fungus | Tricholoma populinum | Poplar Knight | 1 | 2023 |
| fungus | Tricholoma resplendens | a basidiomycete fungus | 1 | 1996 |
| fungus | Tricholoma saponaceum | a fungus | 3 | 2022 |
| fungus | Tricholoma saponaceum var. saponaceum | Soap Tricholoma | 1 | 2013 |
| fungus | Tricholoma scalpturatum | Yellowing Knight | 34 | 2017 |
| fungus | Tricholoma sciodes | Beech Knight | 4 | 2010 |
| fungus | Tricholoma sejunctum | Deceiving Knight | 4 | 1997 |
| fungus | Tricholoma stans | Upright Knight | 2 | 2009 |
| fungus | Tricholoma stiparophyllum | Chemical Knight | 15 | 2023 |
| fungus | Tricholoma sulphurescens | Yellow Staining Knight | 3 | 2009 |
| fungus | Tricholoma sulphureum | Stinky Knight | 18 | 2021 |
| fungus | Tricholoma sulphureum var. sulphureum | Sulphur Knight | 25 | 2010 |
| fungus | Tricholoma terreum | Grey Knight | 44 | 2023 |
| fungus | Tricholoma ustale | Burnt Knight | 2 | 2010 |
| fungus | Tricholoma ustaloides | Charred Knight | 4 | 2005 |
| fungus | Tricholomella constricta | Mealy Domecap | 21 | 2014 |
| fungus | Tricholomopsis rutilans | Plums and Custard | 54 | 2015 |
| fungus | Trichopeziza mollissima | an ascomycete fungus | 3 | 1999 |
| fungus | Trichopeziza sulphurea | Yellow Mascara Disco | 2 | 2008 |
| fungus | Trichothecium roseum | a fungus | 1 | 2010 |
| fungus | Trimmatostroma betulinum | a fungus | 1 | 1999 |
| fungus | Trimmatostroma salicis | a fungus | 2 | 2010 |
| fungus | Triphragmium filipendulae | Dropwort Rust | 2 | 2018 |
| fungus | Triphragmium ulmariae | Meadowsweet Rust | 4 | 2017 |
| fungus | Trochila craterium | Ivy Speckle | 1 | 1998 |
| fungus | Trochila ilicina | Holly Speckle | 52 | 2021 |
| fungus | Tubaria | an agaric (unidentified) | 1 | 1995 |
| fungus | Tubaria confragosa | Ringed Twiglet | 2 | 2002 |
| fungus | Tubaria conspersa | Felted Twiglet | 8 | 2013 |
| fungus | Tubaria dispersa | Hawthorn Twiglet | 38 | 2014 |
| fungus | Tubaria furfuracea | Scurfy Twiglet | 255 | 2024 |
| fungus | Tubaria romagnesiana | an agaric | 3 | 2006 |
| fungus | Tuber aestivum | Summer Truffle | 2 | 2000 |
| fungus | Tuberculina persicina | a fungus | 2 | 2008 |
| fungus | Tuber excavatum | Hollowed Truffle | 1 | 1959 |
| fungus | Tuber foetidum | Stinking Truffle | 1 | 1959 |
| fungus | Tuber puberulum | Downy Truffle | 4 | 2008 |
| fungus | Tuber rapaeodorum | a fungus | 1 | 1959 |
| fungus | Tubeufia cerea | a fungus | 1 | 1991 |
| fungus | Tulasnella pallida | a fungus | 2 | 2008 |
| fungus | Tulasnella violea | a basidiomycete fungus | 1 | 1997 |
| fungus | Tulosesus angulatus | Bishop's Inkcap | 1 | 2008 |
| fungus | Tulosesus callinus | an agaric | 8 | 2013 |
| fungus | Tulosesus canistri | an agaric | 1 | 2007 |
| fungus | Tulosesus ephemerus | Fleeting Inkcap | 7 | 2002 |
| fungus | Tulosesus eurysporus | an agaric | 1 | 2004 |
| fungus | Tulosesus heterosetulosus | Variedcell Inkcap | 2 | 2009 |
| fungus | Tulosesus heterothrix | Hairy Inkcap | 2 | 2009 |
| fungus | Tulosesus hiascens | Splitting Inkcap | 2 | 1998 |
| fungus | Tulosesus impatiens | Impatient Inkcap | 21 | 2023 |
| fungus | Tulosesus pellucidus | Transparent Inkcap | 2 | 1998 |
| fungus | Tulosesus plagioporus | Slantpored Inkcap | 1 | 2014 |
| fungus | Tulosesus subimpatiens | Frustrating Inkcap | 3 | 2012 |
| fungus | Tylopilus felleus | Bitter Bolete | 5 | 2010 |
| fungus | Typhula erythropus | Redleg Club | 3 | 1995 |
| fungus | Typhula phacorrhiza | Tuberous Club | 2 | 2009 |
| fungus | Typhula setipes | a chantarelle | 3 | 2022 |
| fungus | Typhula sphaeroidea | a fungus | 1 | 2020 |
| fungus | Typhula uncialis | a chantarelle | 1 | 2022 |
| fungus | Tyromyces chioneus | a basidiomycete fungus | 2 | 2007 |
| grasshopper, cricket or true cricket | Tetrix | a Tetrix species (unidentified) | 4 | 2023 |
| grasshopper, cricket or true cricket | Tetrix subulata | Slender Ground-hopper | 146 | 2024 |
| grasshopper, cricket or true cricket | Tetrix undulata | Common Ground Hopper | 189 | 2025 |
| grasshopper, cricket or true cricket | Tettigonia viridissima | Great Green Bush Cricket | 78 | 2020 |
| grasshopper, cricket or true cricket | Tettigoniidae | a Tettigoniidae species (unidentified) | 3 | 2018 |
| grasshopper, cricket or true cricket | Tettigoniidae sp. or Gryllidae sp. (unidentified cricket) | a cricket (unidentified) | 42 | 2020 |
| leech, flatworm or ribbon worm | Tetrastemma | a Tetrastemma species (unidentified) | 2 | 1973 |
| leech, flatworm or ribbon worm | Theromyzon tessulatum | duck leech | 48 | 2013 |
| leech, flatworm or ribbon worm | Tricladida | a Tricladida flatworm (unidentified) | 5 | 2013 |
| leech, flatworm or ribbon worm | Trocheta subviridis | a leech | 2 | 2024 |
| leech, flatworm or ribbon worm | Turbellaria | flatworms | 31 | 2018 |
| lichen | Tephromela atra | a lichen | 4 | 2020 |
| lichen | Tephromela atra var. atra | Black Shields | 3 | 2011 |
| lichen | Thalloidima sedifolium | a lichen | 7 | 2018 |
| lichen | Thelidium decipiens | a lichen | 4 | 2018 |
| lichen | Thelidium incavatum | a lichen | 3 | 2018 |
| lichen | Thelidium minutulum | a lichen | 2 | 2020 |
| lichen | Thelotrema lepadinum | a lichen | 5 | 2019 |
| lichen | Toniniopsis aromatica | a lichen | 20 | 2018 |
| lichen | Toniniopsis bagliettoana | a lichen | 3 | 2018 |
| lichen | Toniniopsis verrucarioides | a lichen | 1 | 1991 |
| lichen | Trapelia coarctata | a lichen | 1 | 2002 |
| lichen | Trapelia glebulosa s. lat. | a lichen | 1 | 1985 |
| lichen | Trapelia obtegens | a lichen | 1 | 1985 |
| lichen | Trapeliopsis | a Trapeliopsis species (unidentified) | 1 | 2011 |
| lichen | Trapeliopsis flexuosa | a lichen | 1 | 1991 |
| lichen | Tuckermannopsis chlorophylla | a lichen | 2 | 1996 |
| liverwort | Trichocolea tomentella | Handsome Woollywort | 1 | 1909 |
| liverwort | Tritomaria quinquedentata | Lyon's Notchwort | 2 | 1991 |
| mammal | Talpa europaea | Mole | 1829 | 2025 |
| mammal - marine | Tursiops truncatus | Bottle-nosed Dolphin | 2 | 1986 |
| millipede | Tachypodoiulus niger | White-legged Snake Millipede | 44 | 2023 |
| mollusc | Tandonia | a Tandonia species (unidentified) | 2 | 2023 |
| mollusc | Tandonia budapestensis | Budapest Slug | 15 | 2023 |
| mollusc | Tandonia sowerbyi | Sowerby's Slug | 19 | 2023 |
| mollusc | Tenellia adspersa | Lagoon Sea-slug | 1 | 1974 |
| mollusc | Testacella (Testacella) maugei | Mauge's Shelled Slug | 2 | 2004 |
| mollusc | Theodoxus fluviatilis | River Nerit | 1 | 1900 |
| mollusc | Trochulus | a Trochulus species (unidentified) | 2 | 2023 |
| mollusc | Trochulus hispidus | Hairy Snail | 59 | 2023 |
| mollusc | Trochulus (Trochulus) striolatus | Strawberry Snail | 156 | 2023 |
| moss | Taxiphyllum wissgrillii | Depressed Feather-moss | 5 | 2006 |
| moss | Tetraphis pellucida | Pellucid Four-tooth Moss | 19 | 2023 |
| moss | Thamnobryum | a Thamnobryum species (unidentified) | 1 | 2023 |
| moss | Thamnobryum alopecurum | Fox-tail Feather-moss | 176 | 2023 |
| moss | Thuidium | a Thuidium species (unidentified) | 2 | 1941 |
| moss | Thuidium assimile | Philibert's Tamarisk-moss | 3 | 2016 |
| moss | Thuidium tamariscinum | Common Tamarisk-moss | 93 | 2023 |
| moss | Tortella inflexa | Sassari Crisp-moss | 2 | 2016 |
| moss | Tortella nitida | Neat Crisp-moss | 21 | 2023 |
| moss | Tortella squarrosa | Side-fruited Crisp-moss | 7 | 2023 |
| moss | Tortella tortuosa | Frizzled Crisp-moss | 24 | 2023 |
| moss | Tortula | a Tortula species (unidentified) | 2 | 1941 |
| moss | Tortula acaulon | Cuspidate Earth-moss | 23 | 2023 |
| moss | Tortula caucasica | Blunt-fruited Pottia | 13 | 2023 |
| moss | Tortula lindbergii | Lance-leaved Pottia | 5 | 2023 |
| moss | Tortula marginata | Bordered Screw-moss | 4 | 2017 |
| moss | Tortula muralis | Wall Screw-moss | 154 | 2023 |
| moss | Tortula protobryoides | Tall Pottia | 4 | 2023 |
| moss | Tortula subulata | Awl-leaved Screw-moss | 3 | 2023 |
| moss | Tortula truncata | Common Pottia | 10 | 2023 |
| moss | Tortula viridifolia | Bristly Pottia | 3 | 1990 |
| moss | Trichodon cylindricus | Cylindric Ditrichum | 1 | 1998 |
| moss | Trichostomum brachydontium sensu lato | Variable Crisp-moss | 25 | 2023 |
| moss | Trichostomum crispulum | Curly Crisp-moss | 25 | 2023 |
| moth or butterfly - butterfly | Thecla betulae | Brown Hairstreak | 17 | 2011 |
| moth or butterfly - butterfly | Thymelicus | Essex Skipper or Small Skipper or Lulworth Skipper (unidentified) | 336 | 2025 |
| moth or butterfly - butterfly | Thymelicus lineola | Essex Skipper | 768 | 2025 |
| moth or butterfly - butterfly | Thymelicus sylvestris | Small Skipper | 6736 | 2025 |
| moth or butterfly - macro moth | Tethea ocularis | Figure of Eighty | 274 | 2024 |
| moth or butterfly - macro moth | Tethea ocularis octogesimea | Figure of Eighty | 7 | 2014 |
| moth or butterfly - macro moth | Tethea or | Poplar Lutestring | 16 | 2018 |
| moth or butterfly - macro moth | Tetheella fluctuosa | Satin Lutestring | 34 | 2014 |
| moth or butterfly - macro moth | Thalpophila matura | Straw Underwing | 1115 | 2024 |
| moth or butterfly - macro moth | Thera britannica | Spruce Carpet | 513 | 2024 |
| moth or butterfly - macro moth | Thera cupressata | Cypress Carpet | 607 | 2024 |
| moth or butterfly - macro moth | Thera juniperata | Juniper Carpet | 2 | 2021 |
| moth or butterfly - macro moth | Thera juniperata subsp. juniperata | Juniper Carpet | 14 | 2014 |
| moth or butterfly - macro moth | Thera obeliscata | Grey Pine Carpet | 194 | 2024 |
| moth or butterfly - macro moth | Theria primaria | Early Moth | 144 | 2024 |
| moth or butterfly - macro moth | Tholera cespitis | Hedge Rustic | 40 | 2022 |
| moth or butterfly - macro moth | Tholera decimalis | Feathered Gothic | 51 | 2023 |
| moth or butterfly - macro moth | Thumatha senex | Round-winged Muslin | 53 | 2022 |
| moth or butterfly - macro moth | Thyatira batis | Peach Blossom | 379 | 2024 |
| moth or butterfly - macro moth | Tiliacea aurago | Barred Sallow | 568 | 2024 |
| moth or butterfly - macro moth | Tiliacea citrago | Orange Sallow | 58 | 2024 |
| moth or butterfly - macro moth | Timandra comae | Blood-vein | 1128 | 2025 |
| moth or butterfly - macro moth | Trachea atriplicis | Orache Moth | 1 | 2016 |
| moth or butterfly - macro moth | Trichiura crataegi | Pale Eggar | 28 | 2014 |
| moth or butterfly - macro moth | Trichoplusia ni | Ni Moth (The) | 16 | 2022 |
| moth or butterfly - macro moth | Trichopteryx carpinata | Early Tooth-striped | 38 | 2020 |
| moth or butterfly - macro moth | Trichopteryx polycommata | Barred Tooth-striped | 2 | 1950 |
| moth or butterfly - macro moth | Triodia sylvina | Orange Swift | 1270 | 2025 |
| moth or butterfly - macro moth | Triphosa dubitata | Tissue | 78 | 2024 |
| moth or butterfly - macro moth | Tyria jacobaeae | Cinnabar | 1902 | 2025 |
| moth or butterfly - micro moth | Tachystola acroxantha | Ruddy Streak | 2042 | 2024 |
| moth or butterfly - micro moth | Taleporia tubulosa | Brown Bagworm | 5 | 2013 |
| moth or butterfly - micro moth | Telechrysis tripuncta | Treble-spot | 1 | 2011 |
| moth or butterfly - micro moth | Teleiodes luculella | Crescent Groundling | 13 | 2023 |
| moth or butterfly - micro moth | Teleiodes vulgella | Black-spotted Grey | 132 | 2024 |
| moth or butterfly - micro moth | Teleiopsis diffinis | Large Groundling | 4 | 2020 |
| moth or butterfly - micro moth | Thaumatotibia leucotreta | False Codling Moth | 1 | 1997 |
| moth or butterfly - micro moth | Thiotricha subocellea | Marjoram Case-bearer | 11 | 2024 |
| moth or butterfly - micro moth | Thisanotia chrysonuchella | Powdered Grass-moth | 6 | 2002 |
| moth or butterfly - micro moth | Thyraylia nana | Birch Straw | 7 | 2020 |
| moth or butterfly - micro moth | Tinea columbariella | Dovecot Moth | 1 | 1991 |
| moth or butterfly - micro moth | Tinea pallescentella | Large Pale Clothes Moth | 10 | 2005 |
| moth or butterfly - micro moth | Tinea pellionella | Case-bearing Clothes Moth | 92 | 2023 |
| moth or butterfly - micro moth | Tinea semifulvella | Orange-tipped Nest Moth | 68 | 2023 |
| moth or butterfly - micro moth | Tinea trinotella | Triple-spotted Nest Moth | 112 | 2024 |
| moth or butterfly - micro moth | Tineola bisselliella | Common Clothes Moth | 40 | 2024 |
| moth or butterfly - micro moth | Tischeria dodonaea | Small Oak Blotch-miner | 4 | 2019 |
| moth or butterfly - micro moth | Tischeria ekebladella | Oak Carl | 27 | 2023 |
| moth or butterfly - micro moth | Tortricodes alternella | Spring Harbinger | 29 | 2025 |
| moth or butterfly - micro moth | Tortrix | a Tortrix species (unidentified) | 1 | 2013 |
| moth or butterfly - micro moth | Tortrix viridana | Green Oak Tortrix | 206 | 2024 |
| moth or butterfly - micro moth | Triaxomasia caprimulgella | Tree Hollow Moth | 1 | 2023 |
| moth or butterfly - micro moth | Triaxomera fulvimitrella | Four-spotted Fungus Moth | 1 | 2007 |
| moth or butterfly - micro moth | Triaxomera parasitella | Brindled Fungus Moth | 9 | 2023 |
| moth or butterfly - micro moth | Trifurcula immundella | Broom Dot | 1 | 1906 |
| plant | Taeniatherum caput-medusae | Medusa-head | 3 | 1939 |
| plant | Tagetes erecta | African Marigold | 1 | 1989 |
| plant | Tagetes minuta | Southern Marigold | 3 | 1959 |
| plant | Tagetes patula | French Marigold | 1 | 2014 |
| plant | Tagetes sp. or Calendula sp. or Glebionis sp. or Schkuhria sp. or Caltha sp. or Bidens sp. (unidentified marigold) | a marigold or a marsh marigold or a dwarf marigold or a bur-marigold (unidentified) | 1 | 2015 |
| plant | Tamarix gallica | Tamarisk | 49 | 2017 |
| plant | Tamus communis | Black Bryony | 3930 | 2024 |
| plant | Tanacetum | a Tanacetum species (unidentified) | 1 | 2013 |
| plant | Tanacetum parthenium | Feverfew | 585 | 2025 |
| plant | Tanacetum vulgare | Tansy | 604 | 2024 |
| plant | Taraxacum | Dandelion | 4322 | 2025 |
| plant | Taraxacum acutum | Violet-striped Dandelion | 1 | 2001 |
| plant | Taraxacum agg. | a Plant | 1308 | 2023 |
| plant | Taraxacum ancistrolobum | Few-lobed Dandelion | 2 | 1989 |
| plant | Taraxacum anglicum | English Dandelion | 1 | 1915 |
| plant | Taraxacum atactum | Narrow-bracted Dandelion | 3 | 1991 |
| plant | Taraxacum boekmanii | Bökman's Dandelion | 2 | 1991 |
| plant | Taraxacum brachyglossum | Purple-bracted Dandelion | 6 | 2000 |
| plant | Taraxacum bracteatum | Dark-green Dandelion | 2 | 2016 |
| plant | Taraxacum britannicum | British Dandelion | 5 | 2023 |
| plant | Taraxacum croceiflorum | Orange-flowered Dandelion | 1 | 1991 |
| plant | Taraxacum duplidentifrons | Double-toothed Dandelion | 2 | 1989 |
| plant | Taraxacum exacutum | Imbricate-bracted Dandelion | 1 | 2010 |
| plant | Taraxacum expallidiforme | Broad-stalked Dandelion | 3 | 1992 |
| plant | Taraxacum faeroense | Faeroes Dandelion | 2 | 1940 |
| plant | Taraxacum fulvum | Cinnamon-fruited Dandelion | 1 | 2016 |
| plant | Taraxacum glauciniforme | Many-toothed Dandelion | 1 | 1992 |
| plant | Taraxacum hamatiforme | Asymmetrical Hook-lobed Dandelion | 1 | 2020 |
| plant | Taraxacum hamatulum | Slender Hook-lobed Dandelion | 2 | 1989 |
| plant | Taraxacum hamatum | Hook-lobed Dandelion | 18 | 2020 |
| plant | Taraxacum hamiferum | Dark Hook-lobed Dandelion | 3 | 1989 |
| plant | Taraxacum huelphersianum | Hülphers's Dandelion | 1 | 2010 |
| plant | Taraxacum lacistophyllum | Cut-leaved Dandelion | 7 | 1992 |
| plant | Taraxacum laeticolor | Pale-stalked Dandelion | 1 | 1989 |
| plant | Taraxacum lamprophyllum | Lustrous-leaved Dandelion | 2 | 2020 |
| plant | Taraxacum laticordatum | Decumbent Dandelion | 1 | 1992 |
| plant | Taraxacum latissimum | Broad-leaved Dandelion | 1 | 1989 |
| plant | Taraxacum multicolorans | Many-coloured Dandelion | 4 | 1992 |
| plant | Taraxacum nordstedtii | Nordstedt's Dandelion | 11 | 1992 |
| plant | Taraxacum ochrochlorum | Winged Dandelion | 1 | 1992 |
| plant | Taraxacum oxoniense | Oxford Dandelion | 5 | 1992 |
| plant | Taraxacum pannulatum | Brown-ribbed Dandelion | 1 | 1992 |
| plant | Taraxacum proximum | Umber-fruited Dandelion | 2 | 1991 |
| plant | Taraxacum pseudohamatum | False Hook-lobed Dandelion | 6 | 2020 |
| plant | Taraxacum remanentilobum | Falcate-lobed Dandelion | 1 | 1992 |
| plant | Taraxacum rubicundum | Ruddy Dandelion | 5 | 1992 |
| plant | Taraxacum sect. Erythrosperma | Lesser Dandelion | 18 | 2012 |
| plant | Taraxacum sect. Palustria | a dandelion | 15 | 2000 |
| plant | Taraxacum sect. Vulgaria | a daisy or composite | 45 | 2002 |
| plant | Taraxacum sellandii | Selland's Dandelion | 1 | 1991 |
| plant | Taraxacum subbracteatum | Dark-bracted Dandelion | 4 | 1992 |
| plant | Taraxacum subexpallidum | Tongue-lobed Dandelion | 2 | 2010 |
| plant | Taraxacum subhamatum | Large Hook-lobed Dandelion | 3 | 2020 |
| plant | Taraxacum vastisectum | Crowded-lobed Dandelion | 1 | 2005 |
| plant | Taxodium distichum | Swamp Cypress | 2 | 2000 |
| plant | Taxus | a Taxus species (unidentified) | 7 | 2023 |
| plant | Taxus baccata | Yew | 2005 | 2024 |
| plant | Taxus baccata f. fastigiata | Irish Yew | 3 | 2013 |
| plant | Teesdalia nudicaulis | Shepherd's Cress | 3 | 2013 |
| plant | Tellima grandiflora | Fringe-cups | 26 | 2023 |
| plant | Tetradium daniellii | Korean Euodia | 2 | 2015 |
| plant | Teucrium | a Teucrium species (unidentified) | 1 | 1980 |
| plant | Teucrium botrys | Cut-leaved Germander | 1 | 2005 |
| plant | Teucrium chamaedrys | Wall Germander | 20 | 2019 |
| plant | Teucrium resupinatum | a Plant | 1 | 1925 |
| plant | Teucrium scordium | Water Germander | 1 | 2008 |
| plant | Teucrium scorodonia | Wood Sage | 1079 | 2024 |
| plant | Thalictrum aquilegiifolium | French Meadow-rue | 1 | 1989 |
| plant | Thalictrum flavum | Common Meadow-rue | 112 | 2019 |
| plant | Thalictrum minus | Lesser Meadow-rue | 14 | 2015 |
| plant | Thelypteris palustris | Marsh Fern | 1 | 1930 |
| plant | Thlaspi | a penny-cress (unidentified) | 2 | 2013 |
| plant | Thlaspi arvense | Field Penny-cress | 227 | 2024 |
| plant | Thuja | a thuja (unidentified) | 5 | 2009 |
| plant | Thuja occidentalis | American Arbor-vitae | 67 | 2004 |
| plant | Thuja plicata | Western Red-cedar | 77 | 2023 |
| plant | Thujopsis dolabrata | Hiba | 3 | 2000 |
| plant | Thymus | a thyme (unidentified) | 9 | 2020 |
| plant | Thymus drucei | Wild Thyme | 803 | 2023 |
| plant | Thymus pulegioides | Large Thyme | 130 | 2016 |
| plant | Thymus serpyllum | Breckland Thyme | 3 | 1979 |
| plant | Thymus vulgaris | Thyme | 23 | 2018 |
| plant | Tilia | Linden | 407 | 2024 |
| plant | Tilia cordata | Small-leaved Lime | 527 | 2024 |
| plant | Tilia cordata x dasystyla = T. x euchlora | Caucasian Lime | 2 | 2016 |
| plant | Tilia cordata x platyphyllos = T. x europaea | Common Lime | 911 | 2024 |
| plant | Tilia 'Petiolaris' | Pendent Silver-lime | 18 | 2017 |
| plant | Tilia platyphyllos | Large-leaved Lime | 187 | 2023 |
| plant | Tilia platyphyllos 'Rubra' | Broad Leaved Lime var. Rubra | 1 | 2014 |
| plant | Tilia tomentosa | Silver-lime | 20 | 2022 |
| plant | Torilis | a hedge-parsley (unidentified) | 25 | 2015 |
| plant | Torilis arvensis | Spreading Hedge-parsley | 37 | 2023 |
| plant | Torilis japonica | Upright Hedge-parsley | 1734 | 2024 |
| plant | Torilis leptophylla | a Plant | 1 | 1922 |
| plant | Torilis nodosa | Knotted Hedge-parsley | 121 | 2023 |
| plant | Trachycarpus fortunei | Chusan Palm | 20 | 2000 |
| plant | Trachyspermum ammi | Ajowan | 3 | 1936 |
| plant | Trachystemon orientalis | Abraham-Isaac-Jacob | 12 | 2013 |
| plant | Tragopogon | Goat's-Beard | 5 | 2013 |
| plant | Tragopogon porrifolius | Salsify | 35 | 2020 |
| plant | Tragopogon pratensis | Goat's-beard | 1711 | 2025 |
| plant | Tragopogon pratensis subsp. minor | a goat's-beard | 94 | 2019 |
| plant | Tragopogon pratensis subsp. pratensis | a goat's-beard | 1 | 1984 |
| plant | Tribulus terrestris | Small Caltrops | 2 | 1937 |
| plant | Trichomanes speciosum | Killarney Fern | 7 | 2016 |
| plant | Trichophorum planifolium | Bashful Bulrush | 1 | 1913 |
| plant | Trifolium | Clover | 111 | 2023 |
| plant | Trifolium angustifolium | Narrow Clover | 1 | 1927 |
| plant | Trifolium arvense | Hare's-foot Clover | 37 | 2023 |
| plant | Trifolium aureum | Large Trefoil | 2 | 1999 |
| plant | Trifolium campestre | Hop Trefoil | 803 | 2024 |
| plant | Trifolium diffusum | a Plant | 1 | 1922 |
| plant | Trifolium dubium | Lesser Trefoil | 2583 | 2024 |
| plant | Trifolium fragiferum | Strawberry Clover | 311 | 2025 |
| plant | Trifolium glomeratum | Clustered Clover | 5 | 1998 |
| plant | Trifolium hybridum | Alsike Clover | 213 | 2024 |
| plant | Trifolium incarnatum | Crimson Clover | 1 | 2019 |
| plant | Trifolium incarnatum subsp. incarnatum | Crimson Clover | 1 | 1984 |
| plant | Trifolium lappaceum | Bur Clover | 1 | 1938 |
| plant | Trifolium medium | Zigzag Clover | 223 | 2024 |
| plant | Trifolium micranthum | Slender Trefoil | 112 | 2016 |
| plant | Trifolium ornithopodioides | Bird's-foot clover | 15 | 2014 |
| plant | Trifolium pannonicum | Hungarian Clover | 1 | 1999 |
| plant | Trifolium pratense | Red Clover | 7036 | 2024 |
| plant | Trifolium pratense var. sativum | Red Clover | 5 | 2021 |
| plant | Trifolium purpureum | Purple Clover | 1 | 2014 |
| plant | Trifolium repens | White Clover | 7579 | 2025 |
| plant | Trifolium resupinatum | Reversed Clover | 2 | 1953 |
| plant | Trifolium scabrum | Rough Clover | 90 | 2014 |
| plant | Trifolium squamosum | Sea Clover | 117 | 2016 |
| plant | Trifolium squarrosum | a Plant | 1 | 1955 |
| plant | Trifolium striatum | Knotted Clover | 101 | 2014 |
| plant | Trifolium subterraneum | Subterranean Clover | 21 | 2012 |
| plant | Trifolium suffocatum | Suffocated Clover | 17 | 2015 |
| plant | Trifolium tomentosum | Woolly Clover | 7 | 2008 |
| plant | Triglochin maritima | Sea Arrowgrass | 274 | 2023 |
| plant | Triglochin palustris | Marsh Arrowgrass | 89 | 2018 |
| plant | Trigonella caerulea | Blue Fenugreek | 1 | 1939 |
| plant | Trigonella foenum-graecum | Fenugreek | 2 | 1936 |
| plant | Trigonella glabra | Egyptian Fenugreek | 1 | 1958 |
| plant | Trigonella polyceratia | a Plant | 1 | 1922 |
| plant | Trigonella procumbens | a Plant | 1 | 1922 |
| plant | Trinia glauca | Honewort | 165 | 2023 |
| plant | Tripleurospermum | Mayweed | 2 | 2020 |
| plant | Tripleurospermum decipiens | a Plant | 1 | 1927 |
| plant | Tripleurospermum inodorum | Scentless Mayweed | 1798 | 2024 |
| plant | Tripleurospermum maritimum | Sea Mayweed | 52 | 2016 |
| plant | Tripleurospermum maritimum sens. lat. | Scentless Mayweed agg. | 16 | 2017 |
| plant | Tripleurospermum maritimum subsp. maritimum | a scentless mayweed | 1 | 1984 |
| plant | Tripleurospermum maritimum x inodorum | Mayweed | 3 | 1982 |
| plant | Tripleurospermum sp. or Matricaria sp. | a mayweed or Pineapple Weed (unidentified) | 6 | 2020 |
| plant | Tripolium pannonicum | Sea Aster | 450 | 2023 |
| plant | Tripolium pannonicum subsp. tripolium var. flosculosus | a michaelmas-daisy | 5 | 2015 |
| plant | Trisetum flavescens | Yellow Oat-grass | 1815 | 2023 |
| plant | Tristagma uniflorum | Spring Starflower | 14 | 2023 |
| plant | Triticum | Wheat | 1 | 2024 |
| plant | Triticum aestivum | Bread Wheat | 183 | 2021 |
| plant | Triticum durum | Pasta Wheat | 3 | 1986 |
| plant | Tropaeolum majus | Nasturtium | 20 | 2020 |
| plant | Tsuga | a Tsuga species (unidentified) | 1 | 2000 |
| plant | Tsuga heterophylla | Western Hemlock | 12 | 2011 |
| plant | Tulipa | Tulip | 3 | 2019 |
| plant | Tulipa gesneriana | Garden Tulip | 24 | 2019 |
| plant | Tulipa sylvestris | Wild Tulip | 7 | 2019 |
| plant | Turgenia latifolia | Greater Bur-parsley | 3 | 1939 |
| plant | Turritis glabra | Tower Mustard | 1 | 2011 |
| plant | Tussilago farfara | Colt's-foot | 2026 | 2024 |
| plant | Typha | a Typha species (unidentified) | 11 | 2023 |
| plant | Typha angustifolia | Lesser Bulrush | 31 | 2019 |
| plant | Typha angustifolia x latifolia = T. x glauca | Hybrid Reedmace | 7 | 2006 |
| plant | Typha latifolia | Bulrush | 1109 | 2024 |
| reptile | Trachemys | Slider Terrapins | 1 | 2010 |
| reptile | Trachemys scripta subsp. elegans | Red-eared Terrapin | 2 | 2019 |
| roundworm (nematoda) | Tylenchida | a Tylenchida species (unidentified) | 1 | 2009 |
| sea-fan, sea anemone or jellyfish | Tubularia indivisa | Organ Pipes Hydroid | 10 | 1976 |
| slime mould | Trichia affinis | a slime mould | 4 | 2017 |
| slime mould | Trichia botrytis | a slime mould | 7 | 2017 |
| slime mould | Trichia botrytis var. botrytis | a slime mould | 3 | 2008 |
| slime mould | Trichia contorta | a slime mould | 1 | 2016 |
| slime mould | Trichia decipiens | a slime mould | 3 | 2023 |
| slime mould | Trichia decipiens var. decipiens | a slime mould | 4 | 2008 |
| slime mould | Trichia meylanii | a slime mould | 2 | 2008 |
| slime mould | Trichia munda | a slime mould | 1 | 2008 |
| slime mould | Trichia persimilis | a slime mould | 3 | 2008 |
| slime mould | Trichia scabra | a slime mould | 6 | 2008 |
| slime mould | Trichia varia | a slime mould | 16 | 2017 |
| slime mould | Tubifera ferruginosa | Red Rasberry Slime Mould | 27 | 2022 |
| spider | Talavera aequipes | a jumping spider | 2 | 2016 |
| spider | Tallusia experta | a money spider | 1 | 2019 |
| spider | Tegenaria | a Tegenaria species (unidentified) | 6 | 2017 |
| spider | Tegenaria domestica | Common House Spider | 9 | 2017 |
| spider | Tegenaria silvestris | a cobweb spider | 6 | 2007 |
| spider | Tenuiphantes alacris | a money spider | 3 | 1988 |
| spider | Tenuiphantes flavipes | a money spider | 26 | 2003 |
| spider | Tenuiphantes mengei | a money spider | 10 | 1997 |
| spider | Tenuiphantes tenuis | a money spider | 89 | 2019 |
| spider | Tenuiphantes zimmermanni | a money spider | 38 | 2019 |
| spider | Tetragnatha | a Tetragnatha species (unidentified) | 28 | 2023 |
| spider | Tetragnatha extensa | a long-jawed spider | 48 | 2023 |
| spider | Tetragnatha montana | a long-jawed spider | 96 | 2023 |
| spider | Tetragnatha nigrita | a long-jawed spider | 1 | 2014 |
| spider | Tetragnatha obtusa | a long-jawed spider | 3 | 1985 |
| spider | Tetragnatha pinicola | a long-jawed spider | 2 | 2013 |
| spider | Tetragnatha striata | a long-jawed spider | 5 | 2021 |
| spider | Tetragnathidae | long-jawed spiders | 13 | 2024 |
| spider | Textrix denticulata | a cobweb spider | 13 | 2015 |
| spider | Theridiidae | comb-footed spiders | 35 | 2023 |
| spider | Theridion | a Theridion species (unidentified) | 4 | 2017 |
| spider | Theridion familiare | a comb-footed spider | 1 | 2003 |
| spider | Theridion melanurum | a comb-footed spider | 7 | 2013 |
| spider | Theridion mystaceum | a comb-footed spider | 4 | 2014 |
| spider | Theridion pictum | a comb-footed spider | 7 | 2013 |
| spider | Theridion varians | a comb-footed spider | 14 | 2014 |
| spider | Theridiosoma gemmosum | Ray Spider | 3 | 1999 |
| spider | Thomisidae | crab spiders | 20 | 2023 |
| spider | Thomisidae sp. or Philodromidae sp. (unidentified crab spider) | a crab spider (unidentified) | 12 | 2018 |
| spider | Tibellus maritimus | a running crab spider | 1 | 1999 |
| spider | Tibellus oblongus | a running crab spider | 8 | 2022 |
| spider | Tiso vagans | a money spider | 1 | 1995 |
| spider | Trachyzelotes pedestris | a ground spider | 3 | 2003 |
| spider | Trochosa | a Trochosa wolf spider (unidentified) | 4 | 2023 |
| spider | Trochosa ruricola | a wolf spider | 15 | 2013 |
| spider | Trochosa terricola | a wolf spider | 15 | 2019 |
| spider | Troxochrus scabriculus | a money spider | 2 | 1998 |
| springtail | Tomoceridae | a Tomoceridae species (unidentified) | 1 | 2023 |
| springtail | Tomocerus | a Tomocerus species (unidentified) | 5 | 2017 |
| springtail | Tomocerus minor | a springtail (Collembola) | 2 | 2015 |
| springtail | Tomocerus vulgaris | a springtail (Collembola) | 9 | 2020 |
| stonefly | Taeniopteryx | a Taeniopteryx species (unidentified) | 1 | 2018 |
| thrip | Thripidae | a Thripidae thrip (unidentified) | 1 | 2016 |
| thrip | Thrips flavus | a thrip | 1 | 1993 |
| thrip | Thysanoptera | a thrip (unidentified) | 3 | 2018 |
| tick or mite (acarine) | Tetranychus | a Tetranychus mite (unidentified) | 2 | 2014 |
| tick or mite (acarine) | Tetranychus urticae | a mite | 5 | 2021 |
| tick or mite (acarine) | Trombidium | a Trombidium species (unidentified) | 11 | 2023 |
| tick or mite (acarine) | Trombidium holosericeum | Velvet Mite | 3 | 2020 |
| true fly - | Tachina fera | a parasitic fly | 58 | 2025 |
| true fly - | Tachina grossa | a parasitic fly | 1 | 2023 |
| true fly - | Tachinidae | a Larvaevoridae species (unidentified) | 7 | 2023 |
| true fly - | Tachypeza | a Tachypeza species (unidentified) | 1 | 2023 |
| true fly - | Tanypodinae | a Tanypodinae species (unidentified) | 1 | 1991 |
| true fly - | Tephritidae | a Tephritidae species (unidentified) | 5 | 2018 |
| true fly - | Tephritini | a Tephritini species (unidentified) | 1 | 2023 |
| true fly - | Tephrochlamys flavipes | a fly | 13 | 2021 |
| true fly - | Tephrochlamys rufiventris | a fly | 5 | 2022 |
| true fly - | Tetanocera | a Tetanocera species (unidentified) | 9 | 2023 |
| true fly - | Tetanocera arrogans | a snail-killing fly | 20 | 2013 |
| true fly - | Tetanocera elata | a snail-killing fly | 14 | 2009 |
| true fly - | Tetanocera ferruginea | a snail-killing fly | 9 | 2022 |
| true fly - | Tetanocera hyalipennis | a snail-killing fly | 8 | 2003 |
| true fly - | Tetanocera robusta | a snail-killing fly | 4 | 2002 |
| true fly - | Tetanura | a Tetanura species (unidentified) | 1 | 2012 |
| true fly - | Tetanura pallidiventris | a snail-killing fly | 3 | 2000 |
| true fly - | Thaumatomyia hallandica | a fly | 6 | 2009 |
| true fly - | Thaumatomyia notata | a fly | 19 | 2009 |
| true fly - | Thelaira | a Thelaira species (unidentified) | 1 | 2010 |
| true fly - | Thelaira nigrina | a parasitic fly | 6 | 2020 |
| true fly - | Themira annulipes | a lesser dung fly | 20 | 2022 |
| true fly - | Themira lucida | a lesser dung fly | 3 | 2003 |
| true fly - | Themira minor | a lesser dung fly | 8 | 2008 |
| true fly - | Themira putris | a lesser dung fly | 2 | 2002 |
| true fly - | Themira superba | a lesser dung fly | 1 | 2000 |
| true fly - | Thienemannimyia | a Thienemannimyia species (unidentified) | 1 | 1983 |
| true fly - | Thoracochaeta zosterae | a lesser dung fly | 1 | 2003 |
| true fly - | Thricops foveolatus | a muscid fly | 1 | 1960 |
| true fly - | Thricops semicinereus | a muscid fly | 2 | 2003 |
| true fly - | Thricops simplex | a muscid fly | 1 | 1991 |
| true fly - | Tipuloidea | a Tipuloidea species (unidentified) | 5 | 2023 |
| true fly - | Tipulomorpha | a Tipulomorpha species (unidentified) | 1 | 2023 |
| true fly - | Tomosvaryella kuthyi | a big-headed fly | 1 | 1999 |
| true fly - | Tomosvaryella sylvatica | a big-headed fly | 6 | 2008 |
| true fly - | Toxonevra muliebris | a fly | 6 | 2022 |
| true fly - | Trachysiphonella ruficeps | a fly | 2 | 2006 |
| true fly - | Trachysiphonella scutellata | a fly | 2 | 2006 |
| true fly - | Trichocera | a Trichocera species (unidentified) | 1 | 2018 |
| true fly - | Tricholauxania praeusta | a fly | 13 | 2022 |
| true fly - | Trichomyia urbica | a moth fly | 6 | 2020 |
| true fly - | Trichopalpus fraternus | a dung fly | 5 | 2023 |
| true fly - | Trichosia caudata | a fly | 2 | 2021 |
| true fly - | Tricimba cincta | a fly | 6 | 2008 |
| true fly - | Tricimba lineella | a fly | 1 | 2008 |
| true fly - | Tricogena rubricosa | Red-shinned Woodlouse-fly | 1 | 2000 |
| true fly - | Trigonometopus frontalis | a fly | 1 | 2009 |
| true fly - | Trimerina madizans | a shore fly | 4 | 2004 |
| true fly - | Trixa conspersa | a parasitic fly | 10 | 2019 |
| true fly - | Trypetoptera punctulata | a snail-killing fly | 4 | 2006 |
| true fly - | Typhamyza bifasciata | a fly | 3 | 2009 |
| true fly - cranefly | Tasiocera murina | a cranefly | 1 | 2020 |
| true fly - cranefly | Tipula | a Tipula cranefly (unidentified) | 26 | 2023 |
| true fly - cranefly | Tipula cava | a cranefly | 3 | 1998 |
| true fly - cranefly | Tipula confusa | a cranefly | 10 | 2023 |
| true fly - cranefly | Tipula fascipennis | a cranefly | 8 | 2023 |
| true fly - cranefly | Tipula flavolineata | a cranefly | 3 | 2023 |
| true fly - cranefly | Tipula fulvipennis | a cranefly | 7 | 2022 |
| true fly - cranefly | Tipula irrorata | a cranefly | 3 | 2021 |
| true fly - cranefly | Tipula lateralis | a cranefly | 29 | 2023 |
| true fly - cranefly | Tipula luna | a cranefly | 2 | 2001 |
| true fly - cranefly | Tipula lunata | a cranefly | 10 | 2024 |
| true fly - cranefly | Tipula luteipennis | a cranefly | 1 | 2014 |
| true fly - cranefly | Tipula maxima | a cranefly | 34 | 2023 |
| true fly - cranefly | Tipula obsoleta | a cranefly | 5 | 2022 |
| true fly - cranefly | Tipula oleracea | a cranefly | 65 | 2024 |
| true fly - cranefly | Tipula pabulina | a cranefly | 3 | 2005 |
| true fly - cranefly | Tipula pagana | a cranefly | 6 | 2022 |
| true fly - cranefly | Tipula paludosa | a cranefly | 60 | 2024 |
| true fly - cranefly | Tipula pruinosa | a cranefly | 1 | 1983 |
| true fly - cranefly | Tipula rufina | a cranefly | 3 | 2023 |
| true fly - cranefly | Tipula selene | a cranefly | 1 | 2020 |
| true fly - cranefly | Tipula signata | a cranefly | 2 | 2003 |
| true fly - cranefly | Tipula staegeri | a cranefly | 1 | 2003 |
| true fly - cranefly | Tipula subcunctans | a cranefly | 1 | 2003 |
| true fly - cranefly | Tipula submarmorata | a cranefly | 1 | 2000 |
| true fly - cranefly | Tipula unca | a cranefly | 8 | 2005 |
| true fly - cranefly | Tipula variicornis | a cranefly | 1 | 1996 |
| true fly - cranefly | Tipula varipennis | a cranefly | 1 | 1998 |
| true fly - cranefly | Tipula vernalis | a cranefly | 30 | 2023 |
| true fly - cranefly | Tipula vittata | a cranefly | 8 | 2022 |
| true fly - cranefly | Tipulidae | Cranefly | 95 | 2025 |
| true fly - (diptera) | Tephritis matricariae | an insect - true fly (Diptera) | 5 | 2023 |
| true fly - (diptera) | Thaumatomyia glabra | an insect - true fly (Diptera) | 3 | 2009 |
| true fly - (diptera) | Thripomorpha coxendix | an insect - true fly (Diptera) | 7 | 2013 |
| true fly - (diptera) | Trichinomyia flavipes | an insect - true fly (Diptera) | 1 | 2003 |
| true fly - (diptera) | Trichosia confusa | an insect - true fly (Diptera) | 1 | 2001 |
| true fly - (diptera) | Tricyphona immaculata | an insect - true fly (Diptera) | 11 | 2022 |
| true fly - fly | Tetanocera phyllophora | a snail-killing fly | 1 | 1983 |
| true fly - fly | Tetanocera punctifrons | a snail-killing fly | 6 | 2013 |
| true fly - horse fly | Tabanidae | Horsefly | 18 | 2021 |
| true fly - horse fly | Tabanus | a Tabanus horse fly (unidentified) | 4 | 2021 |
| true fly - horse fly | Tabanus autumnalis | Large Marsh Horsefly | 25 | 2022 |
| true fly - horse fly | Tabanus bovinus | Pale Giant Horsefly | 4 | 2014 |
| true fly - horse fly | Tabanus bromius | Band-eyed Brown Horsefly | 48 | 2024 |
| true fly - hoverfly | Trichopsomyia flavitarsis | a hoverfly | 2 | 2001 |
| true fly - hoverfly | Tropidia scita | a hoverfly | 40 | 2021 |
| true fly - midge, gnat or mosquito | Taxomyia taxi | a gall midge | 17 | 2023 |
| true fly - midge, gnat or mosquito | Tetragoneura sylvatica | a fungus gnat | 2 | 2020 |
| true fly - midge, gnat or mosquito | Trichocera annulata | a winter gnat | 16 | 2022 |
| true fly - midge, gnat or mosquito | Trichocera major | a winter gnat | 2 | 2022 |
| true fly - midge, gnat or mosquito | Trichocera regelationis | a winter gnat | 7 | 2021 |
| true fly - midge, gnat or mosquito | Trichocera saltator | a winter gnat | 3 | 2003 |
| true fly - midge, gnat or mosquito | Trichonta falcata | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Trichonta terminalis | a fungus gnat | 2 | 2020 |
| true fly - midge, gnat or mosquito | Trichonta vitta | a fungus gnat | 3 | 2021 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis bardanae | a gall fly | 7 | 2023 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis formosa | a gall fly | 14 | 2023 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis hyoscyami | a gall fly | 5 | 2002 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis neesii | a gall fly | 46 | 2021 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis ruralis | a gall fly | 2 | 2010 |
| true fly - picture-winged, conopid or stilt-legged fly | Tephritis vespertina | a gall fly | 17 | 2023 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia colon | a gall fly | 2 | 2006 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia longicauda | a gall fly | 21 | 2019 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia ruficauda | a gall fly | 14 | 2022 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia serratulae | a gall fly | 8 | 2008 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia tussilaginis | a gall fly | 18 | 2025 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia vectensis | a gall fly | 2 | 1990 |
| true fly - picture-winged, conopid or stilt-legged fly | Terellia winthemi | a gall fly | 1 | 2006 |
| true fly - picture-winged, conopid or stilt-legged fly | Thecophora atra | a fly | 30 | 2024 |
| true fly - picture-winged, conopid or stilt-legged fly | Thecophora fulvipes | a fly | 11 | 2006 |
| true fly - picture-winged, conopid or stilt-legged fly | Trupanea stellata | a gall fly | 1 | 1994 |
| true fly - picture-winged, conopid or stilt-legged fly | Trypeta artemisiae | a gall fly | 1 | 2016 |
| true fly - picture-winged, conopid or stilt-legged fly | Trypeta zoe | a gall fly | 4 | 2017 |
| true fly - robber, empid or dolichopid fly | Tachydromia aemula | a dance fly | 6 | 2022 |
| true fly - robber, empid or dolichopid fly | Tachydromia arrogans | a dance fly | 1 | 2022 |
| true fly - robber, empid or dolichopid fly | Tachydromia umbrarum | a dance fly | 4 | 2009 |
| true fly - robber, empid or dolichopid fly | Tachypeza fuscipennis | a dance fly | 2 | 2006 |
| true fly - robber, empid or dolichopid fly | Tachypeza nubila | a dance fly | 12 | 2021 |
| true fly - robber, empid or dolichopid fly | Tachytrechus notatus | a dolichopodid fly | 2 | 2002 |
| true fly - robber, empid or dolichopid fly | Teuchophorus calcaratus | a dolichopodid fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Teuchophorus monacanthus | a dolichopodid fly | 1 | 1948 |
| true fly - robber, empid or dolichopid fly | Teuchophorus nigricosta | a dolichopodid fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Teuchophorus simplex | a dolichopodid fly | 2 | 2001 |
| true fly - robber, empid or dolichopid fly | Teuchophorus spinigerellus | a dolichopodid fly | 16 | 2009 |
| true fly - robber, empid or dolichopid fly | Thereva nobilitata | Common Stiletto | 15 | 2017 |
| true fly - robber, empid or dolichopid fly | Thrypticus bellus | a dolichopodid fly | 2 | 2009 |
| true fly - robber, empid or dolichopid fly | Trichina bilobata | a dance fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Trichina clavipes | a dance fly | 2 | 2020 |
| true fly - robber, empid or dolichopid fly | Trichina elongata | a dance fly | 1 | 2021 |
| true fly - robber, empid or dolichopid fly | Trichopeza longicornis | a dance fly | 6 | 2022 |
| water-bear (tardigrade) | Tardigrada | Tardigrade | 1 | 2017 |
| woodlouse | Trachelipus rathkii | a woodlouse | 1 | 1948 |
| woodlouse | Trichoniscus pusillus | Common Pygmy Woodlouse | 32 | 2023 |
| woodlouse | Trichoniscus pygmaeus | a woodlouse | 3 | 2011 |
| worm | Terebella lapidaria | an annelid | 2 | 1936 |
| worm | Tubifex | a Tubifex species (unidentified) | 3 | 2018 |
| worm | Tubifex/Potamothrix sp. | a Tubifex/Potamothrix oligochaete worm (unidentified) | 2 | 2008 |
| worm | Tubifex tubifex | a mud worm | 1 | 2018 |
| worm | Tubificidae | Tubificid Worm Sp. | 5 | 2007 |