Key to Adult Insects


Key to Adult Insects


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 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 lonbg antennae: wing with only one forked vein Hemiptera
Larger insects with short antennae and many wing veins: tails long


6 Forewings forming club-shaped halteres Strepsiptera
Hind wings forming halteres (may be hidden)


7 Forewings hard or leathery Go to 8
All wings membranous


Go to 13
8 Forewings horny apart from membranous tip Hemiptera
Forewings of uniform texture throughout


Go to 9
9 Forewings (elytra) hard and veinless, meeting in centre line Go to 10
Forewings 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 forceps : elytra always short Dermaptera
Abdomen without forceps: elytra commonly cover whole abdomen


11 Insects with peircing 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


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 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 Forewings 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


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


23 Wings noticeably hairy Go to 24
Wings not noticeably hairy


Go to 25
24 All of wings more or less alike: front tarsi swollen Embioptera
Hind wings usually broader than forewings: front tarsi not swollen


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 forewings


27 Hind wings similar to or larger than forewings: abdomen with cerci Plecoptera
Hindwings smaller than forewings: 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


29 Insects with slender, twig like body Phasmida
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 sheild 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 conspicious 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


37 Abdomen with 3 long terminal appendages Thysanura
Abdomen with only 2 terminal appendages


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 springin organ under rear of abdomen: generally found in soilor decaying vegetation Collembola
Insects not like this


Go to 40



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


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 flattened dorso-latterally


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’ insectswith strong claws well suited to clinging to a host mammal Diptera
Antennae long: body somewhat circular, with less prominant legs and claws


45 Prothorax distinct: biting mouths Mallophaga
Thoracic segments fused into one unit: sucking mouths


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 near hind end: insects found on growing plants