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Dichotomous Keys - Text Format.
Arthropods - Key A: Arthropods with Six Legs, with Well-Developed Wings.

Tips: Only adult arthropods are included, and certain uncommon orders are not included. To use a key, read both descriptions in a couplet (for instance, 1a and 1b). Decide which sounds most like your critter, and move to the next couplet indicated. Should you reach a dead-end, use the numbers in parentheses to backtrack until you reach a couplet that you felt unsure about, and try following the other path. Some orders are found more than once in the keys, because the arthropods occur in different forms.

STEP FROM CHARACTERS ORDER / CLASS
1a One pair of wings. . . . . . . . . . go to 2
1b Two pairs of wings. . . . . . . . . . go to 3
2a 1a Hind wings reduced to tiny knobs (halteres), tip of abdomen without 2-3 thread-like tails
DIPTERA
(Flies)
2b 1a Hind wings not reduced to tiny knobs, tip of abdomen with 2-3 thread-like tails (caudal filaments)
EPHEMEROPTERA
(Mayflies)
3a 1b Front and hind wings have similar texture. . . . . . . . . . go to 4
3b 1b Front wings a rigid or leathery covering for clear hind wings. . . . . . . . . . go to 14
4a 3a Wings covered with powdery scales, mouthparts usually a coiled tube (proboscis) for sucking
LEPIDOPTERA
(Moths / Butterflies)
4b 3a Wings not covered with powdery scales, mouthparts not a coiled tube. . . . . . . . . . go to 5
5a 4b Wings slope downwards (rooflike) from the center at rest. . . . . . . . . go to 6
5b 4b Wings not held rooflike at rest. . . . . . . . . . go to 9
6a 5a Wings covered with hair
TRICHOPTERA
(Caddisflies)
6b 5a Hairless wings. . . . . . . . . . go to 7
7a 6b Sucking mouthparts in the form of a rigid beak, often short and bristley antennae, body may look like a thorn
HOMOPTERA
(Hoppers)
7b 6b Mouthparts not in the form of a rigid beak, antennae not short and bristley, body never looks like a thorn. . . . . . . . . . go to 8
8a 7b Wings with many cross veins
NEUROPTERA
(Lacewings)
8b 7b Wings without many cross veins
PSOCOPTERA
(Bark lice)
9a 5b Front and hind wings similar in size and shape. . . . . . . . . . . go to 10
9b 5b Front and hind wings not similar in size and shape. . . . . . . . . .go to 12
10a 9a Antennae always short and bristley
ODONATA
(Dragonflies & Damselflies)
10b 9a Antennae never short and bristley. . . . . . . . . . go to 11
11a 10b Wings held flat over abdomen when at rest, last abdominal segment not enlarged, usually found in colonies
ISOPTERA
(Termites)
11b 10b Wings not held flat over abdomen when at rest, males with the last abdominal segment enlarged like a scorpion's stinger and held over the body, not found in colonies
MECOPTERA
(Scorpionflies)
12a 9b Body very soft, without a narrow "waist". . . . . . . . . . go to 13
12b 9b Body not exceptionally soft, often with a narrow "waist"
HYMENOPTERA
(Bees & Wasps)
13a 12a Hind wings wider than front wings, folded underneath like a fan
PLECOPTERA
(Stoneflies)
13b 12a Hind wings much smaller than front wings, not folded underneath like a fan
EPHEMEROPTERA
(Mayflies)
14a 3b Sucking mouthparts in the form of a rigid beak, front wings with clear tips (hemelytra), overlapping at rest, revealing a triangular panel on the back (scutellum)
HETEROPTERA
(True Bugs)
14b 3b Chewing mouthparts, front wings without clear tips. . . . . . . . . . go to 15
15a 14b Rigid front wings (elytra) meet in a straight line down the middle of the back
COLEOPTERA
(Beetles)
15b 14b Front wings not as above. . . . . . . . . . go to 16
16a 15b Head visible from above. . . . . . . . . . go to 17
16b 15b Head hidden from above by a hoodlike structure (pronotum)
BLATTARIA
(Cockroaches)
17a 16a Front legs strong with prominent spines for grasping prey, hind legs long and slender
MANTODEA
(Mantids)
17b 16a Front legs without spines or with weak spines, the femora of the hind legs are enlarged for jumping
ORTHOPTERA
(Grasshoppers & Crickets)


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