Key to adult insects

A photograph of an adult female Orange Tip butterfly, _Anthocharis cardamines_

An adult female orange tip butterfly, Anthocharis cardamines. Only the adult males possess the orange tips to the wings that give this species its common name.

If you've found an insect and you don't know what it is then you can use the on-line Key below to find out what order your insect belongs to. It is a good idea to have the insect in a 'Bug Box' whilst you use the Key - it's much easier than relying on your memory. Please read all the text below before using the Key.

Limitations of the Key

The AES cannot be held responsible if the Key provides an incorrect identification, it is intended as a guide only - if you require a species level identification then please use our identification services or send the insect with comprehensive details of where you found it to the Entomology Department of your nearest University or Natural History Museum.

Non-members can use the Bug Club discussion forum however membership of this forum is not restricted and we cannot guarantee the help/advice offered.

Key to insect orders

Start at Question 1 and follow the links until you've identified your insect.

  1. Insect has wings? Go to 2
    Insect wingless or with poorly developed (vestigial) wings. Go to 29

  2. One pair of wings. Go to 3
    Two pairs of wings. Go to 7

  3. Body grasshopper-like, with enlarged hind legs and pronotum extending back over abdomen = Orthoptera
    Insects not like this. Go to 4

  4. Abdomen with 'tails'. Go to 5
    Abdomen without 'tails'. Go to 6

  5. Insects <5mm long, with relatively long antennae: wing with only one forked vein = Hemiptera
    Larger insects with short antennae and many wing veins: tails long = Ephemeroptera

  6. Fore wings forming club-shaped halteres = Strepsiptera
    Hind wings forming halteres (may be hidden) = Diptera

  7. Fore wings hard or leathery. Go to 8
    All wings membranous. Go to 13

  8. Fore wings tough apart from membranous tip = Hemiptera
    Fore wings of uniform texture throughout. Go to 9

  9. Fore wings (elytra) hard and veinless, meeting in centre line. Go to 10
    Fore wings with many veins, overlapping at least a little and often held roofwise over the body. Go to 11

  10. Abdomen ending in a pair of pincer-like cerci : elytra always short = Dermaptera
    Abdomen without forceps: elytra commonly cover whole abdomen = Coleoptera

  11. Insects with piercing and sucking beaks = Hemiptera
    Insects with chewing mouthparts: cerci ('tails') usually present. Go to 12

  12. Hind legs modified for jumping = Orthoptera
    Hind legs not modified for jumping. Go to 49

  13. Tiny insects covered with white powder. Go to 14
    Insects not like this. Go to 15

  14. Wings held flat at rest: mouth-parts adapted for piercing and sucking = Hemiptera
    Wings held roofwise over body at rest: biting mouthparts = Neuroptera

  15. Small, slender insects with narrow, hair-fringed wings: often found in flowers = Thysanoptera
    Insects not like this. Go to 16

  16. Head extending downwards into a beak = Mecoptera
    No such beak. Go to 17
  17. Wings more or less covered with scales: coiled proboscis (tongue) usually present = Lepidoptera
    Wings usually transparent although often hairy. Go to 18

  18. Wings with a network of veins, including many cross veins. Go to 19
    Wings with relatively few cross veins. Go to 23

  19. Abdomen with long terminal threads. Go to 20
    Terminal appendages short or absent. Go to 21

  20. Fore wings much larger than hind wings: wings held vertically over body at rest: 2 or 3 terminal threads = Ephemeroptera
    Wings more of less equal in size or hind wings larger: wings folded close to body at rest: 2 terminal appendages = Plecoptera

  21. Antennae very short: body at least 25mm long = Odonata
    Antennae longer: greater than width of head. Go to 22

  22. Tarsi 3-segmented = Plecoptera
    Tarsi 5-segmented = Neuroptera

  23. Wings noticeably hairy. Go to 24
    Wings not noticeably hairy. Go to 25

  24. All wings more or less alike: front tarsi swollen = Embioptera
    Hind wings usually broader than fore wings: front tarsi not swollen = Trichoptera

  25. Tarsi with 4 or 5 segments. Go to 26
    Tarsi with 1 - 3 segments. Go to 27

  26. All wings alike = Isoptera
    Hind wings much smaller than fore wings = Hymenoptera

  27. Hind wings similar to or larger than fore wings: abdomen with cerci = Plecoptera
    Hindwings smaller than fore wings: no cerci. Go to 28

  28. Tiny insects with at least 12 antennal segments = Psocoptera
    Never more than 10 antennal segments: piercing and sucking beak present = Hemiptera

  29. Insects with slender, twig like body = Phasmatodea
    Insects not like this. Go to 30

  30. Insects with grasshopper-like body and long back legs = Orthoptera
    Insects not like this. Go to 31

  31. Small, soft-bodied insects living on plants, often under protective shield or scale = Hemiptera
    Insects not like this. Go to 32

  32. Minute soil-living insects, <2mm long without antennae = Protura
    Insects not like this. Go to 33

  33. Insects with cerci or other abdominal appendages. Go to 34
    Insects with other appendages. Go to 41

  34. Abdominal appendages long and conspicuous. Go to 35
    Abdominal appendages short or hidden under body. Go to 38

  35. Abdominal appendages forming pincers. Go to 36
    Abdominal appendages not forming pincers. Go to 37

  36. Tarsi 3-segmented = Dermaptera
    Tarsi 1-segmented = Diplura

  37. Abdomen with 3 long terminal appendages = Thysanura
    Abdomen with only 2 terminal appendages = Diplura

  38. Tiny jumping insects, head points downwards forming a beak = Mecoptera
    No sign of beak. Go to 39

  39. Small or minute insects with a forked springing organ (furcula) under rear of abdomen: generally found in soil or decaying vegetation = Collembola
    Insects not like this. Go to 40

  40. Tarsi usually 4-segmented = Isoptera
    Tarsi 3-segmented: front tarsi swollen = Embioptera

  41. Parasites in fur or feathers: insects generally flattened side-to-side or dorso-ventrally. Go to 42
    Insects not parasitic and not usually flattened. Go to 46

  42. Jumping insects flattened from side-to-side = Siphonaptera
    Insects not flattened from side-to-side. Go to 43

  43. Insects of moderate size: head partly withdrawn into thorax. Go to 44
    Small minute insects: head not withdrawn into thorax. Go to 45

  44. Antennae very short: very 'leggy' insects with strong claws well suited to clinging to a host mammal = Diptera
    Antennae long: body somewhat circular, with less prominant legs and claws = Hemiptera

  45. Prothorax distinct: biting mouthparts = Mallophaga
    Thoracic segments fused into one unit: sucking mouthparts = Anoplura

  46. Abdomen with pronounced 'waist': antennae often elbowed = Hymenoptera
    No such features. Go to 47

  47. Body >5mm long, clothed with flattened hairs and scales: vestigial wings present = Lepidoptera
    Body usually <5mm long, bald or occasionally scaly: vestigial wings rarely present. Go to 48

  48. Head a wide or nearly as wide as body: biting mouthparts: insects often found among dried materials = Psocoptera
    Head narrower than body: sucking mouthparts: abdomen often with a pair of tubular outgrowths (cornicles) near hind end: insects found on growing plants = Hemiptera
  49. First pair of legs raptorial (used to grasp prey) and held close to the body at rest = Praying Mantids
    Front legs not like this and body flattened = Cockroaches


This Key is based on the Keys that can be found in the following books.

Insects of Britain & Northern Europe
Michael Chinery
Collins Field Guide
ISBN 0-00-219918-1

The Practical Entomologist
Rick Imes
Aurum Press
ISBN 1-85410-209-5

Definitions to some of the terms used in this Key can be found in the Entomologists' Glossary