SIMPLIFIED KEY TO THE PRINCIPAL ORDERS OF INSECTS IN THE ADULT STAGE

by: Walter Ebeling, Professor, UC Berkeley

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QUESTION

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ORDER

1 Wings usually present

Wings absent

2

17

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2 Mouth parts formed for biting

Mouth parts formed for sucking

3

13

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3 Tip of abdomen with paired, forceps-like appendages (earwigs)

Tip of abdomen without paired, forceps-like appendages

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4

DERMAPTERA

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4 Forewings membranous or leathery, not horny in texture

Forewings horny, shield-like, forming cover for hindwings (beetles)

5

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COLEOPTERA

5 Forewings leathery, hindwings folded fanlike (grasshoppers, crickets, cockroaches)

Forewings membranous, hindwings not folded fanlike

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6

ORTHOPTERA

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6 Abdomen usually constricted at base, often with a stinger or specialized ovipositor (ants, bees, wasps)

Abdomen not constricted at base, without a stinger or specialized ovipositor

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7

HYMENOPTERA

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7 Antennae short, inconspicuous

Antennae long or conspicuous

8

9

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8 Hindwings smaller than forewings; abdomen with 2 or 3 threadlike filaments (mayflies)

Hindwings not smaller than forewings, abdomen without long, threadlike filaments (dragonflies, damselflies)

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EPHEMERIDA

ODONATA

9 Tarsi with less than 5 segments

Tarsi 5-segmented

10

11

 
10 Hindwings broader than forewings, folded in repose (stoneflies)

Hindwings same width as forewings, not folded (termites)

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PLECOPTERA

ISOPTERA

11 Wings naked or very slightly hairy

Wings densely clothed with hair (caddisflies)

12

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TRICHOPTERA

12 Head prolonged into beak, with mouthparts at tip (scorpionflies)

Head not prolonged or beaklike (lacewings, ant-lions)

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MECOPTERA

NEUROPTERA

13 Wings densely clothed with scales; mouth parts coiled below head (butterflies, moths)

Wings not clothed with scales; mouth parts not coiled below head

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14

LEPIDOPTERA

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14 Mouthparts sunken into head capsule, asymmetrical; usually very tiny insects; wings with hair fringe (thrips)

Mouthparts external in repose, symmetrical

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15

THYSANOPTERA

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15 Wings usually 4; mouth parts forming a jointed beak

Wings 2; mouth parts stylet-like or sponge-like, not forming a jointed beak (flies)

16

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DIPTERA

16 Basal portion of forewings thickened, leathery, or horny; distal portion membranous (true bugs)

Forewings with same consistency throughout (aphids, scale insects, leafhoppers, cicadas, psyllids)

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HEMIPTERA

HOMOPTERA

17 Abdomen without conspicuous appendages

Abdomen with conspicuous "tails" or "spring"

18

19

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18 Body flattened dorsoventrally; prothorax small, ringlike (lice)

Body flattened laterally; prothorax large and hoodlike (fleas)

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ANOPLURA

SIPHONAPTERA

19 Abdomen 10- or 1l-segmented, terminating in forceps (pincers) or long filaments (silverfish, bristletails)

Abdomen with not more than 6 segments, often terminating in a springing apparatus (springtails)

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THYSANURA

COLLEMBOLA