Key to Adult Insects


Key to Adult Insects


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



1Insect has wings?Go to 2
Insect wingless or with poorly developed wings


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2One pair of wingsGo to 3
Two pairs of wings


Go to 7
3Body grasshopper-like, with enlarged hind legs and pronotum extending back over abdomenOrthoptera
Insects not like this


Go to 4
4Abdomen with ‘tails’Go to 5
Abdomen without ‘tails’


Go to 6
5Insects <5mm long, with relatively lonbg antennae: wing with only one forked veinHemiptera
Larger insects with short antennae and many wing veins: tails long


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


7Forewings hard or leatheryGo to 8
All wings membranous


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8Forewings horny apart from membranous tipHemiptera
Forewings of uniform texture throughout


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9Forewings (elytra) hard and veinless, meeting in centre lineGo to 10
Forewings with many veins, overlapping at least a little and often held roofwise over the body


Go to 11
10Abdomen ending in a pair of forceps : elytra always shortDermaptera
Abdomen without forceps: elytra commonly cover whole abdomen


11Insects with peircing and sucking beaksHemiptera
Insects with chewing mouthparts: cerci (‘tails’) usually present


Go to 12
12Hind legs modified for jumpingOrthoptera
Hind legs not modified for jumping


13Tiny insects covered with white powderGo to 14
Insects not like this


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14Wings held flat at rest: mouth-parts adapted for piercing and suckingHemiptera
Wings held roofwise over body at rest: biting mouthpartsNeuroptera
15Small, slender insects with narrow, hair-fringed wings: often found in flowersThysanoptera
Insects not like this


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16Head extending downwards into a beakMecoptera
No such beak


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17Wings more or less covered scales: coiled proboscis (tongue) usually presentLepidoptera
Wings usually transparent although often hairy


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18Wings with a network of veins, including many cross veinsGo to 19
Wings with relatively few cross veins


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19Abdomen with long terminal threadsGo to 20
Terminal appendages short or absent


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20Forewings much larger than hind wings: wings held vertically over body at rest: 2 or 3 terminal threadsEphemeroptera
Wings more of less equal in size or hind wings larger: wings folded close to body at rest: 2 terminal appendages


21Antennae very short: body at least 25mm longOdonata
Antennae longer: greater than width of head


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22Tarsi 3-segmentedPlecoptera
Tarsi 5-segmented


23Wings noticeably hairyGo to 24
Wings not noticeably hairy


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24All of wings more or less alike: front tarsi swollenEmbioptera
Hind wings usually broader than forewings: front tarsi not swollen


25Tarsi with 4 or 5 segmentsGo to 26
Tarsi with 1 – 3 segments


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26All wings alikeIsoptera
Hind wings much smaller than forewings


27Hind wings similar to or larger than forewings: abdomen with cerciPlecoptera
Hindwings smaller than forewings: no cerci


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28Tiny insects with at least 12 antennal segmentsPsocoptera
Never more than 10 antennal segments: piercing and sucking beak present


29Insects with slender, twig like bodyPhasmida
Insects not like this


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30Insects with grasshopper-like body and long back legsOrthoptera
Insects not like this


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31Small, soft-bodied insects living on plants, often under protective sheild or scaleHemiptera
Insects not like this


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32Minute soil-living insects, <2mm long without antennaeProtura
Insects not like this


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33Insects with cerci or other abdominal appendagesGo to 34
Insects with other appendages


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34Abdominal appendages long and conspiciousGo to 35
Abdominal appendages short or hidden under body


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35Abdominal appendages forming pincersGo to 36
Abdominal appendages not forming pincers


Go to 37
36Tarsi 3-segmentedDermaptera
Tarsi 1-segmented


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


38Tiny jumping insects, head points downwards forming a beakMecoptera
No sign of beak


Go to 39
39Small or minute insects with a forked springin organ under rear of abdomen: generally found in soilor decaying vegetationCollembola
Insects not like this


Go to 40



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


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


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42Jumping insects flattened from side-to-sideSiphonaptera
Insects flattened dorso-latterally


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


Go to 45
44Antennae very short: very ‘leggy’ insectswith strong claws well suited to clinging to a host mammalDiptera
Antennae long: body somewhat circular, with less prominant legs and claws


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


46Abdomen with pronounced ‘waist’: antennae often elbowedHymenoptera
No such features


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


Go to 48
48Head a wide or nearly as wide as body: biting mouthparts: insects often found among dried materialsPsocoptera
Head narrower than body: sucking mouthparts: abdomen often with a pair of tubular outgrowths near hind end: insects found on growing plants