Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| alder fly, lacewing or snake fly | Megaloptera | a Megaloptera species (unidentified) | 3 | 2018 |
| alder fly, lacewing or snake fly | Micromus angulatus | a brown lacewing | 1 | 2009 |
| alder fly, lacewing or snake fly | Micromus paganus | a brown lacewing | 2 | 1990 |
| alder fly, lacewing or snake fly | Micromus variegatus | a brown lacewing | 25 | 2021 |
| algae or stonewort | Microspora | a Microspora green algae (unidentified) | 1 | 2010 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrocentrus bicolor | a braconid wasp | 3 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrocentrus infirmus | a braconid wasp | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrocentrus thoracicus | a braconid wasp | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Macrophya) alboannulata | a sawfly | 1 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Macrophya) annulata | a sawfly | 12 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Macrophya) duodecimpunctata | a sawfly | 2 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Macrophya) ribis | a sawfly | 1 | 1999 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Macrophya) rufipes | a sawfly | 2 | 2012 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macrophya (Pseudomacrophya) punctumalbum | a sawfly | 4 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Macropis europaea | a solitary bee | 1 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile | a Megachile species (unidentified) | 14 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile (Delomegachile) willughbiella subsp. willughbiella (sensu stricto) | an insect - hymenopteran | 3 | 1975 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile (Megachile) centuncularis | Patchwork Leaf-cutter Bee | 40 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile (Megachile) ligniseca | Wood-carving Leaf-cutter Bee | 10 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile (Megachile) versicolor | a solitary bee | 4 | 2004 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile willughbiella | Willughby's Leaf-cutter Bee | 27 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megachile (Xanthosarus) maritima | Coastal Leaf-cutter Bee | 4 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Megastigmus dorsalis | a chalcid wasp | 26 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Melanips opacus | a small parasitic wasp | 2 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Melecta albifrons | a nomad or mason bee | 5 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Melitta haemorrhoidalis | a solitary bee | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Melitta leporina | a solitary bee | 1 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mellinus arvensis | Field Digger Wasp | 13 | 2012 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesochorus fuscicornis | an insect - hymenopteran | 1 | 1994 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesochorus giberius | an insect - hymenopteran | 1 | 1994 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesochorus sylvarum | an insect - hymenopteran | 1 | 1994 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesochorus vittator | an insect - hymenopteran | 2 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesoleptus laevigatus | an insect - hymenopteran | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus amaenus | a chalcid wasp | 2 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus dubius | a chalcid wasp | 2 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus fuscipes | a chalcid wasp | 4 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus sericeus | an insect - hymenopteran | 43 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus teliformis | a chalcid wasp | 1 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mesopolobus tibialis | a chalcid wasp | 14 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Metallus | a Metallus species (unidentified) | 1 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Metallus lanceolatus | a sawfly | 1 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Meteorus | a Meteorus species (unidentified) | 1 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Meteorus cinctellus | a braconid wasp | 1 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Meteorus ictericus | a braconid wasp | 7 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Meteorus pendulus | a braconid wasp | 2 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Meteorus rubens | a braconid wasp | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Microgaster subcompleta | a braconid wasp | 1 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mimesa equestris | a solitary wasp | 1 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Mimumesa dahlbomi | a solitary wasp | 3 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Miscogaster rufipes | a chalcid wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Monodontomerus aereus | a chalcid wasp | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Monophadnoides confusa | an insect - hymenopteran | 2 | 2013 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Monophadnoides tenuicornis | an insect - hymenopteran | 3 | 2004 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Monosapyga clavicornis | a solitary wasp | 1 | 1997 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Monostegia abdominalis | a sawfly | 1 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmecina graminicola | Grass Ant | 4 | 2007 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica | a Myrmica ant (unidentified) | 10 | 2017 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica lobicornis | a Myrmica ant | 1 | 1995 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica rubra | Red Ant | 50 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica ruginodis | a Myrmica ant | 45 | 2018 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica sabuleti | a Myrmica ant | 10 | 2010 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmica scabrinodis | a Myrmica ant | 38 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Myrmosa atra | Black Headed Velvet Ant | 8 | 2013 |
| beetle | Magdalis (Odontomagdalis) armigera | a weevil | 3 | 2001 |
| beetle | Malachius bipustulatus | Malachite Beetle | 119 | 2021 |
| beetle | Malthinus | a Malthinus species (unidentified) | 1 | 2014 |
| beetle | Malthinus balteatus | a soldier beetle | 15 | 2018 |
| beetle | Malthinus flaveolus | a soldier beetle | 24 | 2019 |
| beetle | Malthinus seriepunctatus | a soldier beetle | 17 | 2018 |
| beetle | Malthodes | a Malthodes species (unidentified) | 1 | 2006 |
| beetle | Malthodes crassicornis | a soldier beetle | 1 | 2016 |
| beetle | Malthodes fibulatus | a soldier beetle | 1 | 1991 |
| beetle | Malthodes fuscus | a soldier beetle | 2 | 1999 |
| beetle | Malthodes guttifer | a soldier beetle | 1 | 2000 |
| beetle | Malthodes marginatus | a soldier beetle | 16 | 2019 |
| beetle | Malthodes minimus | a soldier beetle | 18 | 2017 |
| beetle | Malvapion malvae | a seed weevil | 3 | 2014 |
| beetle | Mantura matthewsii | a leaf beetle | 1 | 2018 |
| beetle | Margarinotus carbonarius | a carrion beetle | 1 | 2000 |
| beetle | Margarinotus (Paralister) ventralis | an insect - beetle (Coleoptera) | 1 | 2002 |
| beetle | Margarinotus (Ptomister) brunneus | a carrion beetle | 5 | 2015 |
| beetle | Margarinotus (Ptomister) merdarius | a carrion beetle | 6 | 2016 |
| beetle | Margarinotus (Ptomister) striola | a carrion beetle | 1 | 2017 |
| beetle | Mecinus circulatus | a weevil | 1 | 2018 |
| beetle | Mecinus collaris | a weevil | 9 | 2017 |
| beetle | Mecinus labilis | a weevil | 6 | 2019 |
| beetle | Mecinus pascuorum | a weevil | 45 | 2017 |
| beetle | Mecinus pyraster | a weevil | 34 | 2019 |
| beetle | Medon brunneus | a rove beetle | 2 | 1999 |
| beetle | Megalinus glabratus | a rove beetle | 2 | 2007 |
| beetle | Megarthrus denticollis | a rove beetle | 1 | 1997 |
| beetle | Megarthrus depressus | a rove beetle | 1 | 2016 |
| beetle | Megasternum concinnum | a scavenger water beetle | 26 | 2018 |
| beetle | Melandrya caraboides | a false darkling beetle | 1 | 1994 |
| beetle | Melanophthalma distinguenda | a mould beetle | 1 | 1995 |
| beetle | Melanophthalma suturalis | a Beetle | 2 | 1962 |
| beetle | Melanotus (beetle) | a melanotus beetle (unidentified) | 9 | 2021 |
| beetle | Melanotus castanipes | a Beetle | 8 | 2016 |
| beetle | Melanotus villosus | a click beetle | 33 | 2018 |
| beetle | Melasis buprestoides | a false click beetle | 2 | 2002 |
| beetle | Meligethes | a pollen beetle or sap beetle (unidentified) | 3 | 2017 |
| beetle | Meligethes aeneus | Common Pollen Beetle | 27 | 2018 |
| beetle | Meligethes carinulatus | a pollen or sap beetle | 1 | 2003 |
| beetle | Meligethes erythropus | a pollen or sap beetle | 2 | 1993 |
| beetle | Meligethes flavimanus | a pollen or sap beetle | 3 | 2017 |
| beetle | Meligethes nigrescens | a pollen or sap beetle | 2 | 2002 |
| beetle | Meligethes obscurus | a pollen or sap beetle | 3 | 2003 |
| beetle | Meligethes ruficornis | a pollen or sap beetle | 2 | 2001 |
| beetle | Meligethes solidus | a pollen or sap beetle | 2 | 2003 |
| beetle | Meloe | a Meloe species (unidentified) | 2 | 2021 |
| beetle | Meloe proscarabaeus | Black Oil-beetle | 6 | 2020 |
| beetle | Meloe rugosus | Rugged Oil-beetle | 7 | 2019 |
| beetle | Meloe violaceus | Violet Oil-beetle | 23 | 2020 |
| beetle | Melolontha | a Cockchafer (unidentified) | 10 | 2010 |
| beetle | Melolontha melolontha | Common Cockchafer | 187 | 2021 |
| beetle | Metoecus paradoxus | a wasp-nest beetle | 2 | 2016 |
| beetle | Metopsia clypeata | a rove beetle | 3 | 2018 |
| beetle | Miarus campanulae | a weevil | 2 | 1999 |
| beetle | Micralymma marinum | a rove beetle | 1 | 2015 |
| beetle | Micrambe ulicis | a silken fungus beetle | 2 | 1962 |
| beetle | Microcara testacea | a marsh beetle | 13 | 2018 |
| beetle | Microlestes maurus | a ground beetle | 2 | 2015 |
| beetle | Micropeplus fulvus | a rove beetle | 3 | 2015 |
| beetle | Micropeplus porcatus | a rove beetle | 2 | 2003 |
| beetle | Micropeplus staphylinoides | a rove beetle | 18 | 2016 |
| beetle | Microplontus campestris | a weevil | 6 | 2018 |
| beetle | Microrhagus pygmaeus | a false click beetle | 9 | 2018 |
| beetle | Mocyta fungi | a rove beetle | 4 | 2007 |
| beetle | Mocyta orbata | a rove beetle | 5 | 2003 |
| beetle | Mogulones asperifoliarum | a weevil | 3 | 2016 |
| beetle | Mononychus punctumalbum | Iris Weevil | 2 | 2017 |
| beetle | Monotoma (Monotoma) picipes | a narrow bark beetle | 2 | 2016 |
| beetle | Mordellistena (Mordellina) acuticollis | a tumbling flower beetle | 1 | 2013 |
| beetle | Mordellistena (Mordellistena) neuwaldeggiana | a tumbling flower beetle | 3 | 2016 |
| beetle | Mordellistena (Mordellistena) pumila | a tumbling flower beetle | 4 | 2009 |
| beetle | Mordellochroa abdominalis | a tumbling flower beetle | 7 | 2006 |
| beetle | Mycetophagus atomarius | a hairy fungus beetle | 5 | 2019 |
| beetle | Mycetophagus quadripustulatus | a hairy fungus beetle | 9 | 2018 |
| beetle | Myllaena minuta | a rove beetle | 1 | 1999 |
| beetle | Myrrha | a Myrrha species (unidentified) | 1 | 2014 |
| beetle | Myrrha octodecimguttata | 18-spot Ladybird | 1 | 2010 |
| bird | Mareca strepera | Gadwall | 2548 | 2021 |
| bird | Melanitta fusca | Velvet Scoter | 15 | 2012 |
| bird | Melanitta nigra | Common Scoter | 350 | 2019 |
| bird | Melopsittacus undulatus | Budgerigar | 7 | 2007 |
| bird | Mergellus albellus | Smew | 255 | 2012 |
| bird | Mergus merganser | Goosander | 1771 | 2019 |
| bird | Mergus serrator | Red-breasted Merganser | 337 | 2019 |
| bird | Merops apiaster | Bee-eater | 3 | 2008 |
| bird | Milvus migrans | Black Kite | 2 | 2019 |
| bird | Milvus milvus | Red Kite | 996 | 2021 |
| bird | Morus bassanus | Gannet | 106 | 2019 |
| bird | Motacilla | a wagtail (unidentified) | 46 | 2017 |
| bird | Motacilla alba | Pied Wagtail | 12948 | 2021 |
| bird | Motacilla alba alba | White Wagtail | 398 | 2019 |
| bird | Motacilla cinerea | Grey Wagtail | 5485 | 2021 |
| bird | Motacilla citreola | Citrine Wagtail | 61 | 2019 |
| bird | Motacilla flava | Yellow Wagtail | 4953 | 2020 |
| bird | Motacilla flava flava | Blue-headed Wagtail | 16 | 2019 |
| bird | Motacilla flava subsp. flava x flavissima | Channel Wagtail | 12 | 2019 |
| bird | Motacilla flava subsp. flavissima | a yellow wagtail | 39 | 2007 |
| bird | Motacilla thunbergi | Grey-headed Wagtail | 1 | 2009 |
| bird | Motacillidae | a Motacillidae species (unidentified) | 2 | 2020 |
| bird | Muscicapa striata | Spotted Flycatcher | 3046 | 2021 |
| booklouse or barklouse | Mesopsocus immunis | a booklouse or barklouse | 3 | 2013 |
| bug | Macrolophus rubi | a plantbug or grassbug | 1 | 2016 |
| bug | Macroplax preyssleri | a ground bug | 8 | 2001 |
| bug | Macropsis cerea | a leafhopper | 2 | 2018 |
| bug | Macropsis fuscula | a leafhopper | 2 | 2003 |
| bug | Macropsis scotti | a leafhopper | 2 | 2009 |
| bug | Macropsis scutellata (sensu lato) | Nettle Masked-hopper | 3 | 2020 |
| bug | Macrosiphoniella (Macrosiphoniella) absinthii | Macrosiphoniella (Macrosiphoniella) absinthii | 1 | 2019 |
| bug | Macrosiphum | a Macrosiphum aphid (unidentified) | 1 | 2014 |
| bug | Macrosiphum (Macrosiphum) euphorbiae | Potato Aphid | 22 | 1985 |
| bug | Macrosiphum (Macrosiphum) rosae | Rose Aphid | 3 | 2018 |
| bug | Macrosteles sexnotatus | a leafhopper | 2 | 2008 |
| bug | Macrosteles viridigriseus | a leafhopper | 4 | 2010 |
| bug | Macrotylus (Alloeonycha) paykulli | a plantbug or grassbug | 1 | 2021 |
| bug | Macustus grisescens | a leafhopper | 1 | 2018 |
| bug | Malacocoris chlorizans | Delicate Apple Capsid | 2 | 2015 |
| bug | Mecomma (Mecomma) ambulans | a plantbug or grassbug | 2 | 2020 |
| bug | Megacoelum beckeri | a plantbug or grassbug | 2 | 1999 |
| bug | Megacoelum infusum | a plantbug or grassbug | 7 | 2021 |
| bug | Megaloceroea recticornis | a plantbug or grassbug | 4 | 2018 |
| bug | Megalonotus chiragra | a ground bug | 14 | 2019 |
| bug | Megamelodes quadrimaculatus (sensu lato) | a planthopper | 4 | 2018 |
| bug | Megophthalmus scanicus | a leafhopper | 2 | 1997 |
| bug | Megoura viciae | Vetch Aphid | 2 | 1974 |
| bug | Mesovelia furcata | Pondweed Bug | 5 | 2002 |
| bug | Metatropis rufescens | a stiltbug | 27 | 2018 |
| bug | Metolophium festucae | Fescue Aphid | 8 | 2008 |
| bug | Metopolophium | a Metopolophium species (unidentified) | 1 | 1974 |
| bug | Metopolophium (Metopolophium) dirhodum | Rose-Grain Aphid | 30 | 2010 |
| bug | Metopolophium (Metopolophium) festucae | an aphid | 17 | 1975 |
| bug | Metopolophium (Metopolophium) frisicum | an aphid | 1 | 1975 |
| bug | Microlophium carnosum | Nettle Aphid | 4 | 2015 |
| bug | Micronecta | a Micronecta waterboatman (unidentified) | 3 | 2004 |
| bug | Micronecta (Dichaetonecta) scholtzi | a waterboatman | 5 | 2002 |
| bug | Microvelia (Microvelia) reticulata | a water-cricket | 48 | 2011 |
| bug | Miridae | a Miridae species (unidentified) | 10 | 2018 |
| bug | Miridius quadrivirgatus | a plantbug or grassbug | 11 | 2021 |
| bug | Miris striatus | Fine Streaked Bugkin | 23 | 2019 |
| bug | Mocydia crocea | a leafhopper | 3 | 2019 |
| bug | Mocydiopsis parvicauda | a leafhopper | 1 | 2009 |
| bug | Monalocoris (Monalocoris) filicis | Bracken Bug | 3 | 2018 |
| bug | Muellerianella fairmairei | a planthopper | 2 | 2018 |
| bug | Myrmecoris gracilis | a plantbug or grassbug | 1 | 2009 |
| bug | Myrmus miriformis | a bug | 27 | 2019 |
| bug | Myzocallis (Myzocallis) coryli | Hazel Aphid | 1 | 2015 |
| bug | Myzus (Myzus) cerasi | an aphid | 1 | 2009 |
| bug | Myzus (Myzus) ornatus | Violet Aphid | 21 | 1975 |
| bug | Myzus (Nectarosiphon) ascalonicus | Shallot Aphid | 20 | 1985 |
| bug | Myzus (Nectarosiphon) certus | Violet-Dianthus Aphid | 2 | 1975 |
| bug | Myzus (Nectarosiphon) persicae | Peach-Potato Aphid | 28 | 2018 |
| caddis fly | Melampophylax mucoreus | a caddisfly | 1 | 2018 |
| caddis fly | Micropterna lateralis | a caddisfly | 4 | 2019 |
| caddis fly | Micropterna sequax | a caddisfly | 12 | 2019 |
| caddis fly | Mystacides azurea | a caddisfly | 9 | 2019 |
| caddis fly | Mystacides longicornis | a caddisfly | 27 | 2021 |
| caddis fly | Mystacides nigra | a caddisfly | 1 | 2016 |
| crustacean | Macrocyclops albidus | a crustacean | 6 | 1991 |
| crustacean | Melita palmata | a crustacean | 3 | 1939 |
| crustacean | Mesopodopsis slabberi | a crustacean | 1 | 1921 |
| crustacean | Monocorophium acherusicum | a crustacean | 1 | 1937 |
| crustacean | Monocorophium insidiosum | a sand louse | 1 | 1937 |
| fish | Macroramphosus scolopax | Snipe Fish | 1 | 1902 |
| fish | Maurolicus muelleri | Mueller's Pearlside | 1 | 1861 |
| fish | Melanogrammus aeglefinus | Haddock | 4 | 2002 |
| fish | Merlangius merlangus | Whiting | 12 | 2016 |
| fish | Merluccius merluccius | Hake | 5 | 1987 |
| fish | Mola mola | Sun-fish | 2 | 1900 |
| fish | Molva molva | Ling (fish) | 4 | 2011 |
| fish | Mullus surmuletus | Red Mullet | 3 | 2018 |
| fish | Mustelus asterias | Starry Smooth Hound | 4 | 2015 |
| fish | Mustelus mustelus | Smooth Hound | 3 | 2015 |
| fish | Myoxocephalus scorpius | Short-spined Sea Scorpion | 3 | 1939 |
| fungus | Macrocystidia cucumis | a basidiomycete fungus | 24 | 2014 |
| fungus | Macrocystidia cucumis var. latifolia | a fungus | 1 | 1984 |
| fungus | Macrolepiota excoriata | an agaric | 3 | 2008 |
| fungus | Macrolepiota konradii | an agaric | 5 | 1996 |
| fungus | Macrolepiota mastoidea | an agaric | 78 | 2015 |
| fungus | Macrolepiota procera | Parasol Mushroom | 31 | 2019 |
| fungus | Macrolepiota procera var. procera | a fungus | 17 | 2014 |
| fungus | Macrotyphula | a Macrotyphula species (unidentified) | 1 | 1996 |
| fungus | Macrotyphula fistulosa | a chantarelle | 8 | 2010 |
| fungus | Macrotyphula fistulosa var. fistulosa | Pipe Club | 1 | 2018 |
| fungus | Macrotyphula juncea | a chantarelle | 12 | 2010 |
| fungus | Marasmiellus candidus | a basidiomycete fungus | 9 | 2008 |
| fungus | Marasmiellus ramealis | Twig Parachute | 63 | 2013 |
| fungus | Marasmiellus tricolor | a basidiomycete fungus | 1 | 2000 |
| fungus | Marasmiellus vaillantii | Goblet Parachute | 17 | 2014 |
| fungus | Marasmius bulliardii | a basidiomycete fungus | 8 | 2014 |
| fungus | Marasmius cohaerens | a basidiomycete fungus | 20 | 2020 |
| fungus | Marasmius curreyi | a fungus | 5 | 2014 |
| fungus | Marasmius epiphylloides | a basidiomycete fungus | 10 | 2020 |
| fungus | Marasmius epiphyllus | Leaf Parachute | 40 | 2020 |
| fungus | Marasmius graminum | a basidiomycete fungus | 1 | 1997 |
| fungus | Marasmius oreades | Fairy Ring Champignon | 148 | 2014 |
| fungus | Marasmius rotula | Collared Parachute | 196 | 2020 |
| fungus | Marasmius saccharinus | a basidiomycete fungus | 1 | 2000 |
| fungus | Marasmius setosus | a basidiomycete fungus | 13 | 2014 |
| fungus | Marasmius setosus | a fungus | 4 | 2008 |
| fungus | Marasmius torquescens | a basidiomycete fungus | 40 | 2009 |
| fungus | Marasmius wynneae | a basidiomycete fungus | 60 | 2020 |
| fungus | Marchandiomyces corallinus | a fungus | 1 | 2011 |
| fungus | Massaria inquinans | a fungus | 5 | 2010 |
| fungus | Megacollybia platyphylla | a basidiomycete fungus | 70 | 2020 |
| fungus | Megalocystidium luridum | a basidiomycete fungus | 1 | 2013 |
| fungus | Melampsora caprearum | a fungus | 3 | 2011 |
| fungus | Melampsora caprearum | a rust | 10 | 2011 |
| fungus | Melampsora epitea | a fungus | 2 | 2018 |
| fungus | Melampsora euphorbiae | a rust | 1 | 2012 |
| fungus | Melampsora hypericorum | a rust | 4 | 2008 |
| fungus | Melampsora populnea | a rust | 9 | 2017 |
| fungus | Melampsorella symphyti | a rust | 1 | 2019 |
| fungus | Melampsoridium betulinum | a rust | 7 | 2008 |
| fungus | Melanogaster broomeanus | a fungus | 1 | 1959 |
| fungus | Melanoleuca | a Melanoleuca species (unidentified) | 1 | 1996 |
| fungus | Melanoleuca arcuata | a basidiomycete fungus | 4 | 2006 |
| fungus | Melanoleuca brevipes | a basidiomycete fungus | 12 | 2010 |
| fungus | Melanoleuca cinereifolia | a fungus | 1 | 1994 |
| fungus | Melanoleuca cognata | a fungus | 2 | 2014 |
| fungus | Melanoleuca cognata var. cognata | a basidiomycete fungus | 10 | 2009 |
| fungus | Melanoleuca exscissa var. exscissa | a basidiomycete fungus | 3 | 2007 |
| fungus | Melanoleuca exscissa var. iris | a fungus | 2 | 2011 |
| fungus | Melanoleuca grammopodia | a basidiomycete fungus | 23 | 2014 |
| fungus | Melanoleuca langei | a fungus | 4 | 2014 |
| fungus | Melanoleuca melaleuca | a basidiomycete fungus | 15 | 2014 |
| fungus | Melanoleuca polioleuca | Common Cavalier | 143 | 2020 |
| fungus | Melanoleuca strictipes | a basidiomycete fungus | 5 | 1998 |
| fungus | Melanoleuca stridula | a fungus | 1 | 1996 |
| fungus | Melanoleuca subpulverulenta | a basidiomycete fungus | 1 | 1997 |
| fungus | Melanophyllum eyrei | an agaric | 6 | 2008 |
| fungus | Melanophyllum haematospermum | a fungus | 3 | 2014 |
| fungus | Melanopsamma pomiformis | an ascomycete fungus | 1 | 1999 |
| fungus | Melanotus (fungi) | a Melanotus fungi (unidentified) | 2 | 1977 |
| fungus | Melanotus horizontalis | an agaric | 7 | 2014 |
| fungus | Melanotus phillipsii | an agaric | 5 | 2013 |
| fungus | Melastiza cornubiensis | a fungus | 5 | 2009 |
| fungus | Mensularia radiata | a basidiomycete fungus | 20 | 2020 |
| fungus | Meottomyces dissimulans | an agaric | 12 | 2014 |
| fungus | Meripilus giganteus | Giant Polypore | 23 | 2019 |
| fungus | Microbotryum violaceum | a fungus | 4 | 2011 |
| fungus | Microbotryum violaceum | a rust | 4 | 2014 |
| fungus | Microcalicium | a Microcalicium species (unidentified) | 1 | 2013 |
| fungus | Microcalicium ahlneri | a fungus | 1 | 1988 |
| fungus | Microglossum olivaceum | Earth-tongue | 14 | 2019 |
| fungus | Microglossum viride | an ascomycete fungus | 1 | 2006 |
| fungus | Microthyrium ciliatum var. ciliatum | a fungus | 1 | 1996 |
| fungus | Milesina kriegeriana | a rust | 2 | 2008 |
| fungus | Milesina scolopendrii | a rust | 8 | 2012 |
| fungus | Mitrophora semilibera | a fungus | 3 | 2019 |
| fungus | Miyagia pseudosphaeria | a rust | 3 | 2018 |
| fungus | Mollisia | a Mollisia ascomycete fungus (unidentified) | 7 | 2000 |
| fungus | Mollisia aquosa | an ascomycete fungus | 1 | 1997 |
| fungus | Mollisia cinerea | an ascomycete fungus | 25 | 2020 |
| fungus | Mollisia cinerella | an ascomycete fungus | 3 | 1999 |
| fungus | Mollisia clavata | an ascomycete fungus | 2 | 2010 |
| fungus | Mollisia coerulans | an ascomycete fungus | 2 | 2010 |
| fungus | Mollisia ligni | an ascomycete fungus | 4 | 2012 |
| fungus | Mollisia melaleuca | an ascomycete fungus | 2 | 2001 |
| fungus | Mollisia minutissima | an ascomycete fungus | 1 | 1997 |
| fungus | Morchella elata | a fungus | 5 | 2018 |
| fungus | Morchella esculenta | a fungus | 17 | 2019 |
| fungus | Morchella esculenta var. crassipes | a fungus | 1 | 1986 |
| fungus | Morchella vulgaris | a fungus | 3 | 2006 |
| fungus | Muellerella lichenicola | a lichen | 1 | 1991 |
| fungus | Mutinus caninus | Dog Stinkhorn | 55 | 2014 |
| fungus | Mycena | a Mycena basidiomycete fungus(unidentified) | 3 | 2001 |
| fungus | Mycena abramsii | a basidiomycete fungus | 15 | 2020 |
| fungus | Mycena acicula | a basidiomycete fungus | 41 | 2020 |
| fungus | Mycena adonis | a basidiomycete fungus | 2 | 2011 |
| fungus | Mycena adonis var. adonis | a basidiomycete fungus | 3 | 1999 |
| fungus | Mycena aetites | a basidiomycete fungus | 65 | 2014 |
| fungus | Mycena alcalina | a basidiomycete fungus | 15 | 2006 |
| fungus | Mycena amicta | a basidiomycete fungus | 18 | 2014 |
| fungus | Mycena ammoniaca | a basidiomycete fungus | 1 | 2005 |
| fungus | Mycena arcangeliana | Angel's Bonnet | 50 | 2020 |
| fungus | Mycena atromarginata | a basidiomycete fungus | 1 | 2000 |
| fungus | Mycena bulbosa | a basidiomycete fungus | 1 | 2005 |
| fungus | Mycena capillaripes | a basidiomycete fungus | 8 | 2014 |
| fungus | Mycena capillaris | a basidiomycete fungus | 13 | 2020 |
| fungus | Mycena cinerella | a basidiomycete fungus | 4 | 2010 |
| fungus | Mycena citrinomarginata | a basidiomycete fungus | 4 | 2010 |
| fungus | Mycena clavularis | a basidiomycete fungus | 10 | 2014 |
| fungus | Mycena corynephora | a basidiomycete fungus | 10 | 2020 |
| fungus | Mycena crocata | a basidiomycete fungus | 1 | 1970 |
| fungus | Mycena epipterygia | Yellowleg Bonnet | 22 | 2020 |
| fungus | Mycena erubescens | a basidiomycete fungus | 3 | 2010 |
| fungus | Mycena filopes | a basidiomycete fungus | 227 | 2020 |
| fungus | Mycena flavescens | a basidiomycete fungus | 20 | 2012 |
| fungus | Mycena flavoalba | a basidiomycete fungus | 79 | 2014 |
| fungus | Mycena galericulata | Bonnet Mycena | 208 | 2014 |
| fungus | Mycena galopus | Milking Bonnet | 32 | 2020 |
| fungus | Mycena galopus var. candida | a basidiomycete fungus | 12 | 2012 |
| fungus | Mycena galopus var. galopus | a basidiomycete fungus | 132 | 2010 |
| fungus | Mycena galopus var. nigra | a basidiomycete fungus | 3 | 1996 |
| fungus | Mycena haematopus | a basidiomycete fungus | 89 | 2020 |
| fungus | Mycena hiemalis | a basidiomycete fungus | 19 | 2014 |
| fungus | Mycena inclinata | a basidiomycete fungus | 94 | 2020 |
| fungus | Mycena latifolia | a fungus | 1 | 2010 |
| fungus | Mycena leptocephala | a basidiomycete fungus | 171 | 2020 |
| fungus | Mycena lineata | a basidiomycete fungus | 1 | 2001 |
| fungus | Mycena luteoalba | a fungus | 35 | 2009 |
| fungus | Mycena maculata | a basidiomycete fungus | 1 | 2005 |
| fungus | Mycena megaspora | a basidiomycete fungus | 2 | 2013 |
| fungus | Mycena metata | a basidiomycete fungus | 45 | 2020 |
| fungus | Mycena mirata | a basidiomycete fungus | 2 | 2020 |
| fungus | Mycena olida | a basidiomycete fungus | 48 | 2014 |
| fungus | Mycena olivaceomarginata | a basidiomycete fungus | 73 | 2015 |
| fungus | Mycena pearsoniana | a basidiomycete fungus | 2 | 2020 |
| fungus | Mycena pelianthina | a basidiomycete fungus | 68 | 2020 |
| fungus | Mycena polyadelpha | a basidiomycete fungus | 4 | 2020 |
| fungus | Mycena polygramma | a basidiomycete fungus | 104 | 2020 |
| fungus | Mycena pseudocorticola | a basidiomycete fungus | 18 | 2020 |
| fungus | Mycena pterigena | a basidiomycete fungus | 2 | 2008 |
| fungus | Mycena pura | Lilac Bonnet | 306 | 2020 |
| fungus | Mycena purpureofusca | a basidiomycete fungus | 2 | 2013 |
| fungus | Mycena rorida | a basidiomycete fungus | 27 | 2020 |
| fungus | Mycena rosea | Rosy Bonnet | 44 | 2020 |
| fungus | Mycena rosella | a basidiomycete fungus | 13 | 2014 |
| fungus | Mycena sanguinolenta | a basidiomycete fungus | 23 | 2014 |
| fungus | Mycena seynii | a basidiomycete fungus | 1 | 2007 |
| fungus | Mycena silvae-nigrae | a basidiomycete fungus | 1 | 1993 |
| fungus | Mycena speirea | a basidiomycete fungus | 117 | 2020 |
| fungus | Mycena stipata | a basidiomycete fungus | 13 | 2010 |
| fungus | Mycena stylobates | Bulbous Bonnet | 18 | 2012 |
| fungus | Mycena tenerrima | Frosty Bonnet | 70 | 2020 |
| fungus | Mycena tintinnabulum | a basidiomycete fungus | 2 | 1998 |
| fungus | Mycena vitilis | Snapping Bonnet | 180 | 2020 |
| fungus | Mycena vulgaris | a basidiomycete fungus | 2 | 2000 |
| fungus | Mycenella bryophila | a basidiomycete fungus | 3 | 2005 |
| fungus | Mycenella margaritispora | a basidiomycete fungus | 2 | 1996 |
| fungus | Mycetinis alliaceus | a basidiomycete fungus | 1 | 1999 |
| fungus | Mycetinis scorodonius | a basidiomycete fungus | 1 | 1995 |
| fungus | Mycoacia aurea | a basidiomycete fungus | 8 | 2005 |
| fungus | Mycoacia uda | a basidiomycete fungus | 21 | 2012 |
| fungus | Mycoacia uda | a fungus | 1 | 1970 |
| fungus | Mycopan scabripes | a basidiomycete fungus | 2 | 2002 |
| fungus | Mycosphaerella isariphora | a fungus | 1 | 2011 |
| fungus | Mycosphaerella latebrosa | a fungus | 3 | 2011 |
| fungus | Mycosphaerella plantaginis | a fungus | 1 | 2011 |
| fungus | Myochromella boudieri | a basidiomycete fungus | 4 | 2004 |
| fungus | Myriangium duriaei | a fungus | 1 | 2010 |
| fungus | Myxomphalia maura | a basidiomycete fungus | 1 | 2006 |
| grasshopper, cricket or true cricket | Meconema meridionale | Southern Oak Bush Cricket | 2 | 2016 |
| grasshopper, cricket or true cricket | Meconema thalassinum | Oak Bush Cricket | 152 | 2021 |
| grasshopper, cricket or true cricket | Myrmeleotettix maculatus | Mottled Grasshopper | 67 | 2019 |
| harvestman | Megabunus diadema | a harvestman | 3 | 1999 |
| harvestman | Mitopus morio | a harvestman | 13 | 2017 |
| harvestman | Mitostoma chrysomelas | a harvestman | 2 | 2019 |
| leech, flatworm or ribbon worm | Microplana terrestris | a flatworm | 1 | 2015 |
| lichen | Massjukiella polycarpa | a lichen | 19 | 2013 |
| lichen | Melanelixia fuliginosa | a lichen | 4 | 2004 |
| lichen | Melanelixia glabratula | a lichen | 28 | 2018 |
| lichen | Melanelixia subaurifera | a lichen | 34 | 2019 |
| lichen | Melanohalea exasperata | a lichen | 3 | 2007 |
| lichen | Melanohalea laciniatula | a lichen | 1 | 2005 |
| lichen | Melanomma pulvis-pyrius | a lichen | 5 | 2001 |
| lichen | Micarea denigrata | a lichen | 2 | 2016 |
| lichen | Micarea prasina | a lichen | 1 | 1988 |
| lichen | Myriospora rufescens | a lichen | 1 | 2014 |
| liverwort | Marchantia polymorpha | Common Liverwort | 23 | 2019 |
| liverwort | Marchantiopsida | a liverwort (unidentified) | 5 | 2018 |
| liverwort | Marchesinia mackaii | MacKay's Pouncewort | 8 | 2019 |
| liverwort | Metzgeria consanguinea | Whiskered Veilwort | 12 | 2019 |
| liverwort | Metzgeria fruticulosa (sensu lato) | a liverwort | 2 | 2017 |
| liverwort | Metzgeria furcata | Forked Veilwort | 116 | 2019 |
| liverwort | Metzgeria violacea | Blueish Veilwort | 17 | 2019 |
| liverwort | Microlejeunea ulicina | Fairy Beads | 12 | 2019 |
| mammal | Meles meles | Badger | 4323 | 2021 |
| mammal | Microchiroptera | a Microchiroptera species (unidentified) | 1 | 2011 |
| mammal | Micromys minutus | Harvest Mouse | 64 | 2020 |
| mammal | Microtus agrestis | Field Vole | 325 | 2021 |
| mammal | Muntiacus | a Muntiacus species (unidentified) | 1 | 2019 |
| mammal | Muntiacus reevesi | Muntjac | 152 | 2021 |
| mammal | Muridae | a vole or mouse (unidentified) | 6 | 2015 |
| mammal | Muridae | a vole (unidentified) | 101 | 2018 |
| mammal | Muscardinus avellanarius | Common Dormouse | 1490 | 2021 |
| mammal | Mus musculus | House Mouse | 110 | 2020 |
| mammal | Mustela | Mink or stoat or weasel or ferret or polecat (unidentified) | 5 | 2016 |
| mammal | Mustela erminea | Stoat | 122 | 2020 |
| mammal | Mustela erminea/nivalis | Stoat or Weasel (unidentified) | 3 | 2008 |
| mammal | Mustela furo x putorius | Polecat-ferret | 7 | 2020 |
| mammal | Mustela furo x putorius OR Mustela putorius (unidentified polecat) | Polecat or Polecat-ferret (unidentified Polecat) | 9 | 2015 |
| mammal | Mustela nivalis | Weasel | 169 | 2021 |
| mammal | Mustela putorius | Polecat | 17 | 2020 |
| mammal | Mustela putorius subsp. furo | Feral Ferret | 1 | 2003 |
| mammal | Mustelidae | a Mustelidae species (unidentified) | 1 | 2015 |
| mammal | Myodes glareolus | Bank Vole | 179 | 2020 |
| mammal - bat | Myotis | a Myotis bat (unidentified) | 293 | 2021 |
| mammal - bat | Myotis bechsteinii | Bechstein's Bat | 54 | 2019 |
| mammal - bat | Myotis brandtii | Brandt's Bat | 30 | 2019 |
| mammal - bat | Myotis daubentonii | Daubenton's Bat | 328 | 2021 |
| mammal - bat | Myotis emarginatus | Notch-eared Bat | 1 | 2013 |
| mammal - bat | Myotis mystacinus | Whiskered Bat | 117 | 2019 |
| mammal - bat | Myotis mystacinus/brandtii | Whiskered/Brandt's Bat | 15 | 2017 |
| mammal - bat | Myotis nattereri | Natterer's Bat | 233 | 2021 |
| mammal - marine | Mesoplodon bidens | Sowerby's Beaked Whale | 1 | 2012 |
| mollusc | Macoma balthica | Baltic Tellin | 25 | 2018 |
| mollusc | Merdigera obscura | Lesser Bulin | 36 | 2015 |
| mollusc | Milax gagates | Smooth Jet Slug | 2 | 2008 |
| mollusc | Mollusca | a Mollusca species (unidentified) | 5 | 2017 |
| mollusc | Monacha (Monacha) cantiana | Kentish Snail | 284 | 2019 |
| mollusc | Musculium lacustre | Lake Orb Mussel | 55 | 2013 |
| mollusc | Mya arenaria | Sand Gaper | 2 | 1972 |
| mollusc | Myosotella myosotis | Mouse-eared Snail | 5 | 2017 |
| mollusc | Mytilus edulis | Common Mussel | 7 | 1976 |
| mollusc | Mytilus galloprovincialis | Mediterranean Mussel | 1 | 1976 |
| moss | Microbryum curvicolle | Swan-necked Earth-moss | 2 | 1991 |
| moss | Microbryum davallianum | Smallest Pottia | 3 | 2015 |
| moss | Microbryum rectum | Upright Pottia | 2 | 1991 |
| moss | Microbryum starckeanum | Starke's Pottia | 2 | 1990 |
| moss | Mnium hornum | Swan's-neck Thyme-moss | 88 | 2019 |
| moss | Mnium stellare | Starry Thyme-moss | 7 | 2019 |
| moth or butterfly - butterfly | Maniola jurtina | Meadow Brown | 22453 | 2021 |
| moth or butterfly - butterfly | Maniola jurtina subsp. insularis | Meadow Brown (sub species occurs in Avon) | 657 | 2003 |
| moth or butterfly - butterfly | Maniola sp. or Pyronia sp. | Meadow Brown or Gatekeeper (unidentified) | 2 | 2006 |
| moth or butterfly - butterfly | Melanargia galathea | Marbled White | 7365 | 2021 |
| moth or butterfly - butterfly | Melitaea cinxia | Glanville Fritillary | 120 | 2016 |
| moth or butterfly - macro moth | Macaria alternata | Sharp-angled Peacock | 132 | 2021 |
| moth or butterfly - macro moth | Macaria brunneata | Rannoch Looper | 3 | 2011 |
| moth or butterfly - macro moth | Macaria liturata | Tawny-barred Angle | 174 | 2021 |
| moth or butterfly - macro moth | Macaria notata | Peacock Moth | 11 | 2012 |
| moth or butterfly - macro moth | Macaria wauaria | V-Moth | 26 | 2013 |
| moth or butterfly - macro moth | Macdunnoughia confusa | Dewick's Plusia | 1 | 2011 |
| moth or butterfly - macro moth | Macroglossum stellatarum | Humming-bird Hawk-moth | 491 | 2021 |
| moth or butterfly - macro moth | Macrothylacia rubi | Fox Moth | 18 | 2017 |
| moth or butterfly - macro moth | Malacosoma neustria | Lackey | 976 | 2021 |
| moth or butterfly - macro moth | Mamestra brassicae | Cabbage Moth | 1633 | 2021 |
| moth or butterfly - macro moth | Martania taeniata | Barred Carpet | 2 | 1955 |
| moth or butterfly - macro moth | Meganephria bimaculosa | Double-spot Brocade | 1 | 1904 |
| moth or butterfly - macro moth | Meganola albula | Kent Black Arches | 10 | 2021 |
| moth or butterfly - macro moth | Meganola strigula | Small Black Arches | 3 | 2011 |
| moth or butterfly - macro moth | Melanchra persicariae | Dot Moth | 863 | 2021 |
| moth or butterfly - macro moth | Melanthia procellata | Pretty Chalk Carpet | 211 | 2021 |
| moth or butterfly - macro moth | Menophra abruptaria | Waved Umber | 451 | 2021 |
| moth or butterfly - macro moth | Mesapamea | a Mesapamea species (unidentified) | 95 | 2020 |
| moth or butterfly - macro moth | Mesapamea didyma | Lesser Common Rustic | 307 | 2018 |
| moth or butterfly - macro moth | Mesapamea secalis | Common Rustic | 1958 | 2021 |
| moth or butterfly - macro moth | Mesapamea secalis agg. | Common Rustic agg. | 1012 | 2021 |
| moth or butterfly - macro moth | Mesapamea secalis/didyma | Common Rustic or Lesser Common Rustic (undetermined) | 799 | 2021 |
| moth or butterfly - macro moth | Mesoleuca albicillata | Beautiful Carpet | 15 | 2017 |
| moth or butterfly - macro moth | Mesoligia furuncula | Cloaked Minor | 661 | 2021 |
| moth or butterfly - macro moth | Miltochrista miniata | Rosy Footman | 354 | 2021 |
| moth or butterfly - macro moth | Mimas tiliae | Lime Hawk-moth | 395 | 2021 |
| moth or butterfly - macro moth | Mniotype adusta | Dark Brocade | 24 | 2015 |
| moth or butterfly - macro moth | Moma alpium | Scarce Merveille du Jour | 1 | 2014 |
| moth or butterfly - macro moth | Mormo maura | Old Lady | 186 | 2021 |
| moth or butterfly - macro moth | Mythimna | a Mythimna species (unidentified) | 1 | 2020 |
| moth or butterfly - macro moth | Mythimna albipuncta | White-point | 9 | 2020 |
| moth or butterfly - macro moth | Mythimna conigera | Brown-line Bright Eye | 96 | 2020 |
| moth or butterfly - macro moth | Mythimna ferrago | Clay | 1160 | 2021 |
| moth or butterfly - macro moth | Mythimna impura | Smoky Wainscot | 1886 | 2021 |
| moth or butterfly - macro moth | Mythimna impura subsp. impura | a Smoky Wainscot | 2 | 2004 |
| moth or butterfly - macro moth | Mythimna l-album | L-album Wainscot | 62 | 2021 |
| moth or butterfly - macro moth | Mythimna litoralis | Shore Wainscot | 4 | 2010 |
| moth or butterfly - macro moth | Mythimna pallens | Common Wainscot | 1703 | 2021 |
| moth or butterfly - macro moth | Mythimna pudorina | Striped Wainscot | 21 | 2019 |
| moth or butterfly - macro moth | Mythimna straminea | Southern Wainscot | 119 | 2019 |
| moth or butterfly - macro moth | Mythimna turca | Double Line | 12 | 2019 |
| moth or butterfly - macro moth | Mythimna unipuncta | White-speck | 5 | 2015 |
| moth or butterfly - macro moth | Mythimna vitellina | Delicate | 23 | 2020 |
| moth or butterfly - micro moth | Marasmarcha lunaedactyla | Crescent Plume | 49 | 2021 |
| moth or butterfly - micro moth | Matilella fusca | a pyralid moth | 24 | 2017 |
| moth or butterfly - micro moth | Mecyna asinalis | a pyralid moth | 27 | 2018 |
| moth or butterfly - micro moth | Mecyna flavalis subsp. flaviculalis | a pyralid moth | 3 | 1998 |
| moth or butterfly - micro moth | Merrifieldia baliodactylus | a plume moth | 14 | 2021 |
| moth or butterfly - micro moth | Merrifieldia leucodactyla | a plume moth | 9 | 2014 |
| moth or butterfly - micro moth | Merrifieldia tridactyla | a plume moth | 2 | 1906 |
| moth or butterfly - micro moth | Metalampra italica | a moth | 11 | 2021 |
| moth or butterfly - micro moth | Metzneria aestivella | a micro-moth | 2 | 2004 |
| moth or butterfly - micro moth | Metzneria aprilella | a micro-moth | 1 | 1993 |
| moth or butterfly - micro moth | Metzneria lappella | a micro-moth | 1 | 2004 |
| moth or butterfly - micro moth | Metzneria metzneriella | a micro-moth | 14 | 2018 |
| moth or butterfly - micro moth | Micropterix aruncella | White-barred Gold | 41 | 2021 |
| moth or butterfly - micro moth | Micropterix aureatella | a micro-moth | 1 | 1990 |
| moth or butterfly - micro moth | Micropterix calthella | Plain Gold | 119 | 2020 |
| moth or butterfly - micro moth | Micropterix mansuetella | a micro-moth | 11 | 2011 |
| moth or butterfly - micro moth | Micropterix tunbergella | a micro-moth | 67 | 2020 |
| moth or butterfly - micro moth | Mirificarma lentiginosella | a micro-moth | 1 | 2004 |
| moth or butterfly - micro moth | Mirificarma mulinella | a micro-moth | 3 | 2016 |
| moth or butterfly - micro moth | Mompha | a Mompha species (unidentified) | 19 | 2021 |
| moth or butterfly - micro moth | Mompha bradleyi | a micro-moth | 19 | 2017 |
| moth or butterfly - micro moth | Mompha conturbatella | a micro-moth | 3 | 2017 |
| moth or butterfly - micro moth | Mompha divisella | a micro-moth | 34 | 2019 |
| moth or butterfly - micro moth | Mompha epilobiella | a moth | 68 | 2021 |
| moth or butterfly - micro moth | Mompha jurassicella | a micro-moth | 1 | 2016 |
| moth or butterfly - micro moth | Mompha lacteella | a micro-moth | 6 | 2017 |
| moth or butterfly - micro moth | Mompha langiella | a micro-moth | 35 | 2020 |
| moth or butterfly - micro moth | Mompha locupletella | a micro-moth | 2 | 1999 |
| moth or butterfly - micro moth | Mompha miscella | a micro-moth | 19 | 2021 |
| moth or butterfly - micro moth | Mompha ochraceella | a micro-moth | 38 | 2021 |
| moth or butterfly - micro moth | Mompha propinquella | a micro-moth | 23 | 2019 |
| moth or butterfly - micro moth | Mompha raschkiella | Little Cosmet | 19 | 2016 |
| moth or butterfly - micro moth | Mompha subbistrigella | a micro-moth | 121 | 2021 |
| moth or butterfly - micro moth | Mompha terminella | a micro-moth | 2 | 2003 |
| moth or butterfly - micro moth | Monochroa | aMonochroa micro-moth (unidentified) | 1 | 2006 |
| moth or butterfly - micro moth | Monochroa cytisella | a micro-moth | 5 | 2018 |
| moth or butterfly - micro moth | Monochroa lucidella | a micro-moth | 3 | 2018 |
| moth or butterfly - micro moth | Monochroa palustrellus | a micro-moth | 14 | 2019 |
| moth or butterfly - micro moth | Monochroa tenebrella | a micro-moth | 2 | 2006 |
| moth or butterfly - micro moth | Monopis | a Monopis species (unidentified) | 8 | 2021 |
| moth or butterfly - micro moth | Monopis crocicapitella | a micro-moth | 40 | 2019 |
| moth or butterfly - micro moth | Monopis imella | a micro-moth | 1 | 1995 |
| moth or butterfly - micro moth | Monopis laevigella | Skin Moth | 31 | 2018 |
| moth or butterfly - micro moth | Monopis obviella | a micro-moth | 65 | 2019 |
| moth or butterfly - micro moth | Monopis weaverella | a micro-moth | 102 | 2019 |
| moth or butterfly - micro moth | Morophaga choragella | a micro-moth | 7 | 2016 |
| moth or butterfly - micro moth | Myelois circumvoluta | Thistle Ermine | 500 | 2021 |
| plant | Macleaya | a Macleaya species (unidentified) | 1 | 2015 |
| plant | Macleaya cordata x microcarpa = M. x kewensis | Hybrid Plume-poppy | 2 | 2016 |
| plant | Madia glomerata | Mountain Tarweed | 1 | 1923 |
| plant | Magnolia | a Magnolia species (unidentified) | 85 | 2018 |
| plant | Magnolia Gradiflora | Southern Magnolia | 1 | 2015 |
| plant | Mahonia | an Oregon grape (unidentified) | 8 | 2019 |
| plant | Mahonia aquifolium | Oregon Grape | 52 | 2019 |
| plant | Mahonia japonica | a flowering plant | 1 | 2016 |
| plant | Malcolmia maritima | Virginia Stock | 9 | 2016 |
| plant | Malus | an apple (unidentified) | 355 | 2021 |
| plant | Malus pumila | Apple (cultivar) | 566 | 2019 |
| plant | Malus spectabilis | a rose | 1 | 2018 |
| plant | Malus sylvestris | Crab Apple | 994 | 2020 |
| plant | Malus sylvestris (sens.lat.) | a Plant | 1 | 1984 |
| plant | Malus sylvestris (sens.lat.) | Apple (crab type) | 291 | 2008 |
| plant | Malva | a mallow (unidentified) | 17 | 2020 |
| plant | Malva alcea | Greater Musk-mallow | 1 | 1999 |
| plant | Malva arborea | Tree-mallow | 162 | 2019 |
| plant | Malva moschata | Musk-mallow | 768 | 2021 |
| plant | Malva neglecta | Dwarf Mallow | 150 | 2019 |
| plant | Malva nicaeensis | French Mallow | 1 | 1937 |
| plant | Malva parviflora | Least Mallow | 1 | 1984 |
| plant | Malva pusilla | Small Mallow | 1 | 1938 |
| plant | Malva setigera | Rough Marsh-mallow | 6 | 2010 |
| plant | Malva sylvestris | Common Mallow | 1727 | 2021 |
| plant | Malva verticillata | Chinese Mallow | 1 | 1985 |
| plant | Mantisalca salmantica | a flowering plant | 3 | 1922 |
| plant | Marrubium vulgare | White Horehound | 8 | 2015 |
| plant | Matricaria | a Matricaria species (unidentified) | 1 | 2004 |
| plant | Matricaria chamomilla | Scented Mayweed | 829 | 2019 |
| plant | Matricaria discoidea | Pineapple Weed | 2677 | 2020 |
| plant | Matteuccia struthiopteris | Ostrich Fern | 1 | 2013 |
| plant | Matthiola incana | Hoary Stock | 8 | 2005 |
| plant | Maytenus boaria | Maiten | 1 | 2018 |
| plant | Meconopsis cambrica | Welsh Poppy | 126 | 2019 |
| plant | Medicago | a Medicago species (unidentified) | 2 | 2005 |
| plant | Medicago arabica | Spotted Medick | 552 | 2020 |
| plant | Medicago arborea | Tree Medick | 9 | 2006 |
| plant | Medicago intertexta | a flowering plant | 1 | 1932 |
| plant | Medicago lupulina | Black Medick | 4241 | 2021 |
| plant | Medicago minima | Bur Medick | 3 | 2006 |
| plant | Medicago noeana | a flowering plant | 1 | 1937 |
| plant | Medicago orbicularis | a flowering plant | 1 | 1941 |
| plant | Medicago polymorpha | Toothed Medick | 43 | 2014 |
| plant | Medicago rigidula | a flowering plant | 1 | 1953 |
| plant | Medicago sativa | Medick | 31 | 2019 |
| plant | Medicago sativa subsp. falcata | Sickle Medick | 7 | 2008 |
| plant | Medicago sativa subsp. sativa | Lucerne | 92 | 2018 |
| plant | Medicago truncatula | Strong-spined Medick | 2 | 1984 |
| plant | Melampodium | a Melampodium species (unidentified) | 1 | 2007 |
| plant | Melampyrum pratense | Common Cow-wheat | 42 | 2018 |
| plant | Melica uniflora | Wood Melick | 811 | 2019 |
| plant | Melilotus | a melilot (unidentified) | 25 | 2020 |
| plant | Melilotus albus | White Melilot | 82 | 2018 |
| plant | Melilotus altissimus | Tall Melilot | 588 | 2020 |
| plant | Melilotus indicus | Small Melilot | 10 | 2005 |
| plant | Melilotus messanensis | Sicilian Melilot | 3 | 1937 |
| plant | Melilotus officinalis | Ribbed Melilot | 96 | 2017 |
| plant | Melilotus sulcatus | Furrowed Melliot | 3 | 1939 |
| plant | Melissa officinalis | Balm | 142 | 2019 |
| plant | Mentha | a mint (unidentified) | 33 | 2016 |
| plant | Mentha aquatica | Water Mint | 1713 | 2021 |
| plant | Mentha aquatica x spicata = M. x piperita | Peppermint | 2 | 1985 |
| plant | Mentha aquatica x suaveolens = M. x suavis | a mint | 1 | 1990 |
| plant | Mentha arvensis | Corn Mint | 222 | 2021 |
| plant | Mentha arvensis x aquatica = M. x verticillata | a Plant | 2 | 2010 |
| plant | Mentha arvensis x aquatica = M. x verticillata | Whorled Mint | 18 | 2012 |
| plant | Mentha arvensis x aquatica x spicata = M. x smithiana | Tall Mint | 6 | 1985 |
| plant | Mentha arvensis x spicata = M. x gracilis | Bushy Mint | 4 | 1984 |
| plant | Mentha longifolia | a Plant | 1 | 2006 |
| plant | Mentha pulegium | Pennyroyal | 2 | 2017 |
| plant | Mentha spicata | Spear Mint | 109 | 2018 |
| plant | Mentha spicata x suaveolens = M. x villosa | a garden apple-mint | 12 | 2013 |
| plant | Mentha spicata x suaveolens = M. x villosa | Apple-mint | 6 | 2015 |
| plant | Mentha suaveolens | Round-leaved Mint | 7 | 2018 |
| plant | Mentha suaveolens x longifolia = M. x rotundifolia | False Apple-mint | 4 | 1992 |
| plant | Mentha x villosa var. villosa | a garden apple-mint | 1 | 2004 |
| plant | Mentzelia albicaulis | White-stemmed Stickleaf | 1 | 1917 |
| plant | Menyanthes trifoliata | Bogbean | 33 | 2020 |
| plant | Mercurialis annua | Annual Mercury | 1155 | 2019 |
| plant | Mercurialis perennis | Dog's Mercury | 4931 | 2021 |
| plant | Mespilus germanica | Medlar | 15 | 2017 |
| plant | Metasequoia glyptostroboides | Dawn Redwood | 25 | 2015 |
| plant | Meum athamanticum | Spignel | 1 | 2015 |
| plant | Milium effusum | Wood Millet | 619 | 2019 |
| plant | Mimulus | a monkeyflower (unidentified) | 1 | 1995 |
| plant | Mimulus guttatus | Monkeyflower | 8 | 2007 |
| plant | Mimulus guttatus x cupreus = M. x burnetii | Coppery Monkeyflower | 1 | 2002 |
| plant | Mimulus guttatus x luteus = M. x robertsii | a monkeyflower | 4 | 1988 |
| plant | Mimulus luteus | Blood-drop Emlets | 3 | 2002 |
| plant | Mimulus moschatus | Musk | 1 | 1994 |
| plant | Minuartia hybrida | Fine-leaved Sandwort | 18 | 2007 |
| plant | Miscanthus sinensis | a Plant | 1 | 2016 |
| plant | Misopates orontium | Weasel's-snout | 7 | 2007 |
| plant | Moehringia trinervia | Three-nerved Sandwort | 635 | 2019 |
| plant | Moenchia erecta | Upright Chickweed | 10 | 1998 |
| plant | Molinia caerulea | Purple Moor-grass | 169 | 2019 |
| plant | Molinia caerulea subsp. arundinacea | a purple moor-grass | 1 | 2007 |
| plant | Molinia caerulea subsp. caerulea | a purple moor-grass | 1 | 2007 |
| plant | Monolepis nuttalliana | Povertyweed | 1 | 1917 |
| plant | Monotropa hypopitys | Yellow Bird's-nest | 22 | 2015 |
| plant | Monotropa hypopitys subsp. hypophegea | a yellow bird's-nest | 1 | 1986 |
| plant | Monotropa hypopitys subsp. hypopitys | a yellow bird's-nest | 2 | 1991 |
| plant | Montia fontana | Blinks | 40 | 2010 |
| plant | Montia fontana subsp. chondrosperma | a blinks | 8 | 2007 |
| plant | Morus | a Morus mulberry (unidentified) | 16 | 2017 |
| plant | Morus nigra | Black Mulberry | 8 | 2017 |
| plant | Muscari | a grape hyacinth (unidentified) | 3 | 2015 |
| plant | Muscari armeniacum | Garden Grape-hyacinth | 140 | 2019 |
| plant | Muscari botryoides | Compact Grape-hyacinth | 10 | 1990 |
| plant | Muscari comosum | Tassel Hyacinth | 1 | 1985 |
| plant | Muscari neglectum | Grape-hyacinth | 77 | 2019 |
| plant | Myagrum perfoliatum | Mitre Cress | 3 | 1954 |
| plant | Mycelis muralis | Wall Lettuce | 662 | 2019 |
| plant | Myosotis | a forget-me-not (unidentified) | 207 | 2021 |
| plant | Myosotis arvensis | Field Forget-me-not | 2382 | 2021 |
| plant | Myosotis arvensis var. sylvestris | a field forget-me-not | 34 | 2014 |
| plant | Myosotis discolor | Changing Forget-me-not | 133 | 2019 |
| plant | Myosotis laxa | Tufted Forget-me-not | 179 | 2017 |
| plant | Myosotis laxa subsp. caespitosa | a Plant | 6 | 2017 |
| plant | Myosotis ramosissima | Early Forget-me-not | 197 | 2021 |
| plant | Myosotis scorpioides | Water Forget-me-not | 498 | 2021 |
| plant | Myosotis secunda | Creeping Forget-me-not | 20 | 2018 |
| plant | Myosotis sylvatica | Wood Forget-me-not | 281 | 2019 |
| plant | Myosoton aquaticum | Water Chickweed | 335 | 2018 |
| plant | Myriophyllum | a water-milfoil (unidentified) | 14 | 2008 |
| plant | Myriophyllum alterniflorum | Alternate Water-milfoil | 13 | 2013 |
| plant | Myriophyllum aquaticum | Parrot's Feather | 28 | 2019 |
| plant | Myriophyllum spicatum | Spiked Water-milfoil | 118 | 2017 |
| plant | Myriophyllum verticillatum | Whorled Water-milfoil | 37 | 2013 |
| plant | Myrrhis | a Myrrhis species (unidentified) | 1 | 2013 |
| plant | Myrrhis odorata | Sweet Cicely | 1 | 2018 |
| scorpion fly (including snow flea) | Mecoptera | a Mecoptera species (unidentified) | 3 | 2014 |
| slime mould | Metatrichia floriformis | a slime mould | 6 | 2017 |
| slime mould | Mucilago crustacea | a slime mould | 28 | 2017 |
| slime mould | Myxogastrea | a slime mould (unidentified) | 1 | 2012 |
| spider | Macrargus rufus | a money spider | 1 | 1985 |
| spider | Malthonica silvestris | a cobweb spider | 6 | 2007 |
| spider | Mangora acalypha | an orb-weaver spider | 2 | 2000 |
| spider | Maso sundevalli | a money spider | 6 | 1991 |
| spider | Meioneta innotabilis | a money spider | 1 | 2010 |
| spider | Meioneta mollis | a money spider | 1 | 1997 |
| spider | Meioneta rurestris | a money spider | 29 | 2003 |
| spider | Meioneta saxatilis (sensu lato) | a money spider | 2 | 2003 |
| spider | Meioneta saxatilis (sensu lato) | a spider (Araneae) | 2 | 1965 |
| spider | Meta | a Meta species (unidentified) | 4 | 2013 |
| spider | Meta bourneti | an orb-weaver spider | 2 | 2013 |
| spider | Meta menardi | Cave Spider | 55 | 2017 |
| spider | Metellina | a Metellina species (unidentified) | 3 | 2015 |
| spider | Metellina mengei | an orb-weaver spider | 64 | 2019 |
| spider | Metellina merianae | an orb-weaver spider | 21 | 2018 |
| spider | Metellina segmentata | an orb-weaver spider | 44 | 2018 |
| spider | Metellina segmentata (sensu lato) | an orb-weaver spider | 19 | 2007 |
| spider | Micaria pulicaria | a ground spider | 10 | 2016 |
| spider | Micrargus apertus | a money spider | 7 | 2003 |
| spider | Micrargus herbigradus (sensu stricto) | a spider (Araneae) | 2 | 1996 |
| spider | Micrargus subaequalis | a money spider | 4 | 2003 |
| spider | Microlinyphia pusilla | a money spider | 13 | 2016 |
| spider | Microneta viaria | a money spider | 28 | 2011 |
| spider | Minyriolus pusillus | a money spider | 2 | 1985 |
| spider | Misumena vatia | a crab spider | 113 | 2021 |
| spider | Moebelia penicillata | a money spider | 1 | 1987 |
| spider | Monocephalus castaneipes | a money spider | 3 | 1999 |
| spider | Monocephalus fuscipes | a money spider | 5 | 1996 |
| true fly - | Macquartia | a Macquartia species (unidentified) | 2 | 2016 |
| true fly - | Macquartia dispar | a parasitic fly | 1 | 2001 |
| true fly - | Macquartia grisea | a parasitic fly | 1 | 2008 |
| true fly - | Macropelopia | a Macropelopia species (unidentified) | 1 | 1983 |
| true fly - | Medina luctuosa | a parasitic fly | 1 | 2001 |
| true fly - | Medina separata | a parasitic fly | 1 | 2004 |
| true fly - | Megaselia | a Megaselia species (unidentified) | 6 | 2008 |
| true fly - | Megaselia emarginata | a scuttle fly | 2 | 2003 |
| true fly - | Megaselia fuscinervis | a scuttle fly | 1 | 2001 |
| true fly - | Megaselia ruficornis | a scuttle fly | 1 | 1995 |
| true fly - | Meigenia mutabilis | a parasitic fly | 2 | 2013 |
| true fly - | Meiosimyza decipiens | a fly | 3 | 2009 |
| true fly - | Meiosimyza platycephala | a fly | 4 | 2006 |
| true fly - | Meiosimyza rorida | a fly | 29 | 2008 |
| true fly - | Meiosimyza subfasciata | a fly | 3 | 2013 |
| true fly - | Melanagromyza aenea | a leaf-mining fly | 1 | 2003 |
| true fly - | Melanagromyza angeliciphaga | a leaf-mining fly | 1 | 2001 |
| true fly - | Melanagromyza cunctans | a leaf-mining fly | 6 | 2008 |
| true fly - | Melanagromyza pubescens | a leaf-mining fly | 1 | 2004 |
| true fly - | Melanomya nana | a fly | 28 | 2009 |
| true fly - | Melanophora roralis | a fly | 9 | 2019 |
| true fly - | Melieria crassipennis | a fly | 1 | 2020 |
| true fly - | Melieria omissa | a fly | 1 | 2009 |
| true fly - | Melieria picta | a fly | 3 | 2019 |
| true fly - | Melinda gentilis | a blue bottle or green bottle | 1 | 2007 |
| true fly - | Meoneura minutissima | a fly | 1 | 2001 |
| true fly - | Meoneura vagans | a fly | 3 | 2003 |
| true fly - | Meromyza | a Meromyza species (unidentified) | 4 | 2013 |
| true fly - | Meromyza athletica | a fly | 3 | 2008 |
| true fly - | Meromyza femorata agg. | a fly | 7 | 2008 |
| true fly - | Meromyza pratorum agg. | a fly | 1 | 2000 |
| true fly - | Meromyza triangulina | a fly | 2 | 2001 |
| true fly - | Mesembrina meridiana | Noon Fly | 107 | 2021 |
| true fly - | Metopina oligoneura | a scuttle fly | 3 | 1995 |
| true fly - | Metopina ulrichi | a scuttle fly | 3 | 2003 |
| true fly - | Metriocnemus | a Metriocnemus species (unidentified) | 1 | 1983 |
| true fly - | Miltogramma | a Miltogramma species (unidentified) | 1 | 2015 |
| true fly - | Miltogramma punctata | a flesh fly | 2 | 1999 |
| true fly - | Minettia | a Minettia species (unidentified) | 2 | 2016 |
| true fly - | Minettia fasciata | a fly | 10 | 2008 |
| true fly - | Minettia inusta | a fly | 4 | 2011 |
| true fly - | Minettia longipennis | a fly | 11 | 2019 |
| true fly - | Minettia rivosa | a fly | 29 | 2013 |
| true fly - | Minettia tabidiventris | a fly | 1 | 2009 |
| true fly - | Minettia tubifer | a fly | 2 | 2009 |
| true fly - | Minilimosina vitripennis | a lesser dung fly | 3 | 2003 |
| true fly - | Mintho rufiventris | a parasitic fly | 2 | 2019 |
| true fly - | Morellia aenescens | a muscid fly | 7 | 2013 |
| true fly - | Morellia simplex | a muscid fly | 2 | 2000 |
| true fly - | Musca autumnalis | Face Fly | 9 | 2013 |
| true fly - | Musca domestica | House Fly | 13 | 2015 |
| true fly - | Muscidae | a Muscidae muscid fly (unidentified) | 6 | 2013 |
| true fly - | Muscina levida | a muscid fly | 4 | 2008 |
| true fly - | Muscina prolapsa | a muscid fly | 5 | 2011 |
| true fly - | Muscina stabulans | a muscid fly | 1 | 1979 |
| true fly - | Mycophaga testacea | a fly | 1 | 1999 |
| true fly - | Mydaea corni | a muscid fly | 3 | 2012 |
| true fly - | Mydaea urbana | a muscid fly | 1 | 2000 |
| true fly - | Myopa | a Myopa species (unidentified) | 1 | 2006 |
| true fly - | Myopina myopina | a fly | 1 | 2003 |
| true fly - | Myospila meditabunda | a muscid fly | 4 | 2012 |
| true fly - cranefly | Molophilus appendiculatus | a cranefly | 1 | 1999 |
| true fly - cranefly | Molophilus bifidus | a cranefly | 1 | 1983 |
| true fly - cranefly | Molophilus cinereifrons | a cranefly | 2 | 2000 |
| true fly - cranefly | Molophilus griseus | a cranefly | 7 | 2009 |
| true fly - cranefly | Molophilus medius | a cranefly | 2 | 1999 |
| true fly - cranefly | Molophilus obscurus | a cranefly | 25 | 2013 |
| true fly - cranefly | Molophilus ochraceus | a cranefly | 1 | 2003 |
| true fly - cranefly | Molophilus pleuralis | a cranefly | 4 | 2009 |
| true fly - cranefly | Molophilus serpentiger | a cranefly | 2 | 2000 |
| true fly - cranefly | Molophilus undulatus | a cranefly | 1 | 2000 |
| true fly - (diptera) | Machimus cingulatus | an insect - true fly (Diptera) | 1 | 2016 |
| true fly - (diptera) | Medetera bispinosa | an insect - true fly (Diptera) | 1 | 1999 |
| true fly - (diptera) | Melinda viridicyanea | an insect - true fly (Diptera) | 3 | 2013 |
| true fly - (diptera) | Meromyza zachvatkini | an insect - true fly (Diptera) | 1 | 2001 |
| true fly - (diptera) | Merzomyia westermanni | an insect - true fly (Diptera) | 6 | 2013 |
| true fly - (diptera) | Metalimnobia quadrinotata | an insect - true fly (Diptera) | 2 | 1999 |
| true fly - (diptera) | Metasyrphus latifasciatus | an insect - true fly (Diptera) | 7 | 1999 |
| true fly - (diptera) | Metasyrphus latilunulatus | an insect - true fly (Diptera) | 1 | 1997 |
| true fly - (diptera) | Metasyrphus nitens | an insect - true fly (Diptera) | 1 | 1916 |
| true fly - hoverfly | Mallota cimbiciformis | a hoverfly | 2 | 1999 |
| true fly - hoverfly | Megasyrphus annulipes | a hoverfly | 2 | 1994 |
| true fly - hoverfly | Melangyna | a Melangyna hoverfly (unidentified) | 3 | 2016 |
| true fly - hoverfly | Melangyna cincta | a hoverfly | 11 | 2020 |
| true fly - hoverfly | Melangyna compositarum | a hoverfly | 10 | 2013 |
| true fly - hoverfly | Melangyna compositarum/labiatarum | a hoverfly | 1 | 2011 |
| true fly - hoverfly | Melangyna labiatarum | a hoverfly | 22 | 2016 |
| true fly - hoverfly | Melangyna lasiophthalma | a hoverfly | 16 | 2008 |
| true fly - hoverfly | Melangyna quadrimaculata | a hoverfly | 2 | 1929 |
| true fly - hoverfly | Melangyna triangulifera | a hoverfly | 4 | 1998 |
| true fly - hoverfly | Melangyna umbellatarum | a hoverfly | 14 | 2018 |
| true fly - hoverfly | Melanogaster aerosa | Dark Melanogaster | 1 | 1995 |
| true fly - hoverfly | Melanogaster hirtella | Common Marsh Hoverfly | 23 | 2016 |
| true fly - hoverfly | Melanostoma | a Melanostoma hoverfly (unidentified) | 7 | 2016 |
| true fly - hoverfly | Melanostoma mellinum | a hoverfly | 112 | 2019 |
| true fly - hoverfly | Melanostoma scalare | a hoverfly | 207 | 2020 |
| true fly - hoverfly | Meliscaeva auricollis | a hoverfly | 61 | 2019 |
| true fly - hoverfly | Meliscaeva cinctella | a hoverfly | 31 | 2018 |
| true fly - hoverfly | Merodon equestris | Greater Bulb-fly | 137 | 2020 |
| true fly - hoverfly | Myathropa florea | Batman Hoverfly | 236 | 2020 |
| true fly - midge, gnat or mosquito | Macrocera anglica | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Macrocera angulata | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Macrocera centralis | a fungus gnat | 6 | 2001 |
| true fly - midge, gnat or mosquito | Macrocera fasciata | a fungus gnat | 5 | 2003 |
| true fly - midge, gnat or mosquito | Macrocera longibrachiata | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Macrocera phalerata | a fungus gnat | 3 | 2001 |
| true fly - midge, gnat or mosquito | Macrocera stigmoides | a fungus gnat | 3 | 2001 |
| true fly - midge, gnat or mosquito | Macrocera vittata | a fungus gnat | 5 | 2001 |
| true fly - midge, gnat or mosquito | Macrodiplosis dryobia | a gall midge | 5 | 1999 |
| true fly - midge, gnat or mosquito | Macrodiplosis pustularis | a gall midge | 1 | 1997 |
| true fly - midge, gnat or mosquito | Macropelopia nebulosa | a non-biting midge | 2 | 2021 |
| true fly - midge, gnat or mosquito | Macrorrhyncha flava | a fungus gnat | 2 | 1997 |
| true fly - midge, gnat or mosquito | Megophthalmidia crassicornis (nomen nudum) | a fungus gnat | 2 | 2014 |
| true fly - midge, gnat or mosquito | Metriocnemus atriclavus | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Metriocnemus eurynotus | a non-biting midge | 4 | 1983 |
| true fly - midge, gnat or mosquito | Microtendipes pedellus | a non-biting midge | 1 | 1983 |
| true fly - midge, gnat or mosquito | Monoclona rufilatera | a fungus gnat | 3 | 2003 |
| true fly - midge, gnat or mosquito | Mycetophila abiecta | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycetophila adumbrata | a fungus gnat | 4 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila britannica | a fungus gnat | 5 | 2003 |
| true fly - midge, gnat or mosquito | Mycetophila cingulum | a fungus gnat | 2 | 2006 |
| true fly - midge, gnat or mosquito | Mycetophila curviseta | a fungus gnat | 14 | 2002 |
| true fly - midge, gnat or mosquito | Mycetophila dentata | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycetophila edwardsi | a fungus gnat | 10 | 2003 |
| true fly - midge, gnat or mosquito | Mycetophila formosa | a fungus gnat | 3 | 2000 |
| true fly - midge, gnat or mosquito | Mycetophila fraterna | a fungus gnat | 3 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila fungorum | a fungus gnat | 3 | 2020 |
| true fly - midge, gnat or mosquito | Mycetophila ichneumonea | a fungus gnat | 2 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila lunata | a fungus gnat | 3 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila marginata | a fungus gnat | 6 | 2002 |
| true fly - midge, gnat or mosquito | Mycetophila mitis | a fungus gnat | 1 | 2003 |
| true fly - midge, gnat or mosquito | Mycetophila ocellus | a fungus gnat | 4 | 2002 |
| true fly - midge, gnat or mosquito | Mycetophila ornata (nomen nudum) | a fungus gnat | 7 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila pumila | a fungus gnat | 3 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila signatoides | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycetophila strigata | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila sumavica | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila trinotata | a fungus gnat | 6 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila unicolor | a fungus gnat | 1 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila unipunctata | a fungus gnat | 2 | 2001 |
| true fly - midge, gnat or mosquito | Mycetophila vittipes | a fungus gnat | 3 | 2003 |
| true fly - midge, gnat or mosquito | Mycomya annulata | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycomya cinerascens | a fungus gnat | 5 | 2001 |
| true fly - midge, gnat or mosquito | Mycomya flavicollis | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycomya marginata | a fungus gnat | 2 | 2001 |
| true fly - midge, gnat or mosquito | Mycomya occultans | a fungus gnat | 2 | 2001 |
| true fly - midge, gnat or mosquito | Mycomya tenuis | a fungus gnat | 2 | 2003 |
| true fly - midge, gnat or mosquito | Mycomya trilineata | a fungus gnat | 1 | 2000 |
| true fly - midge, gnat or mosquito | Mycomya winnertzi | a fungus gnat | 5 | 2001 |
| true fly - picture-winged, conopid or stilt-legged fly | Micropeza lateralis | a stilt fly | 2 | 2016 |
| true fly - picture-winged, conopid or stilt-legged fly | Myopa buccata | a fly | 16 | 2011 |
| true fly - picture-winged, conopid or stilt-legged fly | Myopa extricata | a fly | 10 | 1995 |
| true fly - picture-winged, conopid or stilt-legged fly | Myopa tessellatipennis | a fly | 3 | 1997 |
| true fly - picture-winged, conopid or stilt-legged fly | Myopa testacea | a fly | 9 | 2013 |
| true fly - picture-winged, conopid or stilt-legged fly | Myopites inulaedyssentericae | a gall fly | 4 | 2017 |
| true fly - robber, empid or dolichopid fly | Machaerium maritimae | a dolichopodid fly | 3 | 2000 |
| true fly - robber, empid or dolichopid fly | Machimus atricapillus | Kite-tailed Robberfly | 34 | 2019 |
| true fly - robber, empid or dolichopid fly | Medetera abstrusa | a dolichopodid fly | 2 | 2001 |
| true fly - robber, empid or dolichopid fly | Medetera jacula | a dolichopodid fly | 1 | 2009 |
| true fly - robber, empid or dolichopid fly | Medetera jugalis | a dolichopodid fly | 1 | 2004 |
| true fly - robber, empid or dolichopid fly | Medetera nitida | a dolichopodid fly | 1 | 1986 |
| true fly - robber, empid or dolichopid fly | Medetera pallipes | a dolichopodid fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Medetera saxatilis | a dolichopodid fly | 4 | 2004 |
| true fly - robber, empid or dolichopid fly | Medetera tristis | a dolichopodid fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Medetera truncorum | a dolichopodid fly | 16 | 2019 |
| true fly - robber, empid or dolichopid fly | Micromorphus albipes | a dolichopodid fly | 12 | 2009 |
| true fly - robber, empid or dolichopid fly | Microphor holosericeus | a dance fly | 6 | 2006 |
| true fly - soldier or snipe fly | Microchrysa cyaneiventris | a soldier fly | 2 | 2000 |
| true fly - soldier or snipe fly | Microchrysa flavicornis | a soldier fly | 24 | 2019 |
| true fly - soldier or snipe fly | Microchrysa polita | a soldier fly | 23 | 2019 |
| tunicate (urochordata) | Molgula citrina | Sea Grapes | 1 | 1937 |
| worm | Murchieona muldali | an earthworm | 6 | 2013 |