1. Key to the Orders of Adult Insects
1a – Wings present and well developed although sometimes short…..2
1b – Wings absent, or very small with only inconspicuous remnants present…..26

2. 2a – One pair of wings present….3
2b- Two pair of wings present…..7
3a- Hind wing broad and fanlike; minute, slender, often clubbed appendages replace front wings; 1 or more antennal segments with a long side branch; less than 4 mm long; uncommon (male) Strepsiptera (in part)

3. 3b – Not with above combination of characteristics…….4
4a(3b) – Pronotum very long and extends over or beyond abdomen (easily mistaken for front wings); miniature-sized grasshopper….Orthoptera (in part)
4b – Pronotum not greatly elongated or extending over abdomen; does not resemble grasshopper………5

4. 5a(4b) – One to 3 slender tails on tip of abdomen’ mouthparts poorly developed and inconspicuous……….6
5b – No tails on tip of abdomen; mouthparts usually elongated into a proboscis……Diptera (in part)

5. 6a(5a) – Antennae long and easily visable; wings with only 1 vein (usually forked); minute, slender appendages (halteres) in place of hind wings; 1 spine like appendage sometimes on tip of abdomen; uncommon (suborder Homopters)…Hemiptera (in part)
6b – Antennae very short and bristle like; wings with many veins; halteres absent; 2-3 long, slender tails on tip of abdomen ….. Ephemeroptera (in part)

6. 7a(2b) – Front and hind wings dissimilar in structure; front wings leathery ( thickened and toughened) at their base or for their full length. Or distinctly hard; hind wings membranous if present…….8
7b - Front and hind wings similar in structure; all being membranous or covered with hairs or colored powdery scales, but not leathery or hard……….13

7. 8a(7a) – Mouthparts almost always elongated into a slender beak…..9
8b – Mouthparts not elongated into a beak, but are a chewing type with mandibles and palpi…..10

8. 9a(8a) – Beak arises below and toward the front head; basal portion of front wings hardened and outer portion membranous, or if outer portion not membranous then entire wing is sculptured and lacelike; wings at rest held flat over body (suborder Heteroptera) Hemiptera (in part)

9. 9b – Beak arises below and toward the rear of head or appears to arise between front coxae; front wings uniformly and slightly hardened; wings at rest are held roof like or vertically over body (suborder Homoptera)…Hemoptera (in part)

10. 10a(8b) – Pincer like appendages at tip of abdomen; front wings short…
10a(8b) – Pincer like appendages at tip of abdomen; front wings short….Dermaptera (in part)
10b – No pincer like appendages at tip of abdomen; front wings variable in length……11

11. 11a(10b) – Front wings leathery or hard, without veins, and meet in a straight line down middle of back….Coleoptera
11b – Front wings leathery, veined, and either overlap or are held roof like over body…..12

12. 12a(11b) – Tarsi 3 or 4 segmented; hind legs enlarged and thickened for jumping……Orthoptera
12b – Tarsi 5 segmented; hind legs long and slender for running; front legs may be thickened, spined, and used for grasping……Dictyoptera (in part)

13. 13a(7b) – Wings completely or partly covered with scales (often powdery); mouthparts usually appear as a coiled tube (proboscis)….Lepidoptera (in part)
13 b – Wings not covered with scales; mouthparts not a coiled tube…..14

14. 14a(13b) – Mouthparts elongated into slender beak attached underneath and to the rear of the head, sometimes appearing to arise between the front legs; wings held roof like over body (suborder Homoptera)….Hemiptera (in part)
14b – Not as above…….15

15. 15a(14b) – Front wings triangular and much larger than the small hind wings; wings at rest held vertically above body; 2 or 3 very long, thread like tails at tip of abdomen…..Ephemeroptera (in part)
15b – Not with above combination of characteristics…….16

16. 16a(15b) – Wings very narrow and margined with a fringe of long hairs; usually less than 5 mm long…..Thysanoptera (in part)
16b – Wings not unusually narrow and fringe of hair absent…..17

17. 17a(16b) – Tarsi with 4 or fewer segments….18
17b – Tarsi with 5 segments……23

18. 18a(17a) – Front and hind wings long and similar in length and shape; wings at rest held out to side or above body; abdomen very long and slender….Odonata
18b – Not with above combination of characteristics……..19

19. 19a(18b) – Wings nearly equal in size, shape, and venation; tarsi 4-segmented…….Isoptera (in part)
19b – Front wings longer than hind wings; tarsi with 3 or fewer segments…20

20. 20a(19b) – Hind wings very broad, anal area greatly expanded and folded lengthwise at rest; body generally flattened; tip of abdomen usually with 2 short tails……Plecoptera
20b – Hind wings not usually broad, anal area not extended or folded at rest; body not flattened; short abdominal tails present or absent….21

21. 21a(20b) – Base of front tarsi very stout; tarsi 3 segmented; uncommon….Embioptera (in part)
21b – Base of front tarsi not enlarged; tarsi 2 or 3 segmented……22

22. 22a(21b) – Tip of abdomen with 2 very short tails; tarsi 2 segmented; antennae 9 segmented and bead like; uncommon…..Zoraptera (in part)
22b – Tip of abdomen without short tails; tarsi 2 or 3 segmented; antennae not bead like, but long and thin….Psocoptera (in part)

23. 23a(17b) – Front wings hairy, and with few cross veins along anterior margin; thread like antennae nearly as long as, to much longer than body; mouthparts indistinct except for palpi; moth like…Trichoptera
23b – Front wings not hairy, sometimes many cross veins along anterior margin; antennae distinctly shorter than body; mandibles well developed; generally not moth like…..24

24. 24a(23b) – Front wings longer and with more veins than hind wings; body stout or constricted juncture between thorax and abdomen; needle like (sting0 or saw like appendage on tip of female’s abdomen….Hymenoptera (in part)

25. 24b – Front and hind wings very similar in size and number of veins; body not stout, no constriction between thorax and abdomen; needle like or saw like appendage on tip of abdomen absent although tip of abdomen may be greatly enlarged and curved upward…..25

26. 25a(24b) – Head extended downward to form a stout beak…
25a(24b) – Head extended downward to form a stout beak….Mecopters (in part)
25b – Head does not form a stout beak…Neuroptera

27. 26a(1b) – Head and legs indistinct; covered with soft or hard, waxy coating and attached to plants or if no covering, it occurs as as internal parasite of other insects….27
26b – Head and legs distinct; only a few with threadlike or powdery, waxy coverings….28

28. 27a(26a) – Round to enlongated; sooft or hard, waxy coating; usually attached in clusters to plant (suborder Homoptera) ……Hemiptera (in part)
27b – Elongated; no coating on body, internal parasite of bees, wasps, leafhoppers, others….Strepsiptera (in part)

29. 28a(26b) – Body very flattened either from the side or from top to bottom; external parasites of birds, mammals, or honey bees…….29
28b – Body usually not flattened, but if so then 2 or 3 short to long tails are present on the tip of the abdomen; not parasitic…33

30. 29a(28a) – Tarsi with 3 or fewer segments…30
29b – Tarsi with 5 segments….32
30a(29a) – Antennae longer than head; tarsi 3 segmented (suborder Heteroptera)..Hemiptera
30b – Antennae equal to or shorter than head; tarsi 1 or 2 segmented….31

31. 31a(30b) – Head generally narrower than prothorax and often relatively small; 1 large tarsal claw; thumb like process on tibia…..Anoplura
31b – Head equal in width to or wider than prothorax; 1 or 2 small tarsal claws; tibia without a thumb like process…Mallophaga

32. 32a(29b) – Body flattened from top to bottom; does not jump; primarily on birds and sheep, rarely on bats and honey bees…..Diptera (in part)
32b - Body flattened from the side; jumping insects with long legs…Siphonaptera

33. 33a(28b) – Tip of abdomen with 2 or 3 short to long, slender tails….34
33b - Tip of abdomen with slender tails….35
34a(33a) – Tip of abdomen with 2 tails; body not scaly…Diplura (in part)
34b - Tip of abdomen with 3 tails; body often scaly…..Thysanura

34. 35a(33b) – Tip of abdomen with 2 pincer like appendages……36
35b - Tip of abdomen without 2 pincer like appendages……37
36a(35a) – Tarsi 3 segmented; eyes present and distinct….Dermapters (in part)
36b - Tarsi 1 segmented; eyes absent …Diplura (in part)

35. 37a(35b) – Tarsi 1 to 3 segmented…..38
38a(37a) – Antennae absent; less than 2mm in length; uncommon….Protura
38b – Antennae present; size variable…39

36. 39a(38b) – Body very slender; mouthparts cone-shaped’ tarsi 1 or 2 segmented and often with pad instead of claws at tip; 5mm of less in length…..Thysanoptera (in part)
39b – Body oval or elongated, if very slender then body is more than 5mm long; mouthparts not cone-shaped although they may be long and slender; tarsi 2 or 3 segments or appear to be absent, claws instead of pad present at tip…..40

37. 40a(39b) – Mouthparts form a slender beak…………..41
40b - Mouthparts do not form a slender beak…………..42

38. 41a(40a) – Beak arises underneath toward the rear of head; a pair or tubes may be present near the end of the abdomen; usually more than 5 antennal segments (suborder Homoptera)…..Hemiptera (in part)
41b - Beak arises underneath toward the front of head; abdominal tubes absent; usually 4 to5 antennal segments; may be ant like (suborder Heteroptera)..Hemiptera (in part)

39. 42a(40b) – Hind legs thickened and lengthened for jumping…
42a(40b) – Hind legs thickened and lengthened for jumping….Orthoptera (in part)
42b - Hind legs not thickened and lengthened………..43

40. 43a(42b) – Base of front tarsi very stout; tarsi 3 segmented; uncommon….Embioptera (in part)
43b - Base of front tarsi not stout; tarsi 2 or 3 segmented or may appear to be absent…44

41. 44a(43b) – Antennae threadlike and with 13 or more segments…Psocoptera (in part)
44b - Antennae beadlike or relatively stout with up to 9 segments………45

42. 45a(44b) – Antennae with 9 segments; abdomen with 2 short tails; uncommon…Zoraptera (in part)
45b - Antennae with 6 or fewer segments; abdomen without tails but forked, ventral appendage often present…Collembola

43. 46a(37b) – Distinct constriction or joint between thorax and abdomen; body may be very fuzzy and ant like…Hymenoptera (in part)
46b – No distinct constriction between thorax and abdomen; if body is fuzzy it is not ant like…….47

44. 47a(46b) – Head prolonged into a stout ventral beak…
47a(46b) – Head prolonged into a stout ventral beak…..Mecoptera (in part)
47b - Head not prolonged into a stout ventral beak…….48

45. 48a(47b) – Body densely covered with hairs or scales; coiled proboscis usually present…..Lepidoptera (in part)
48b - Body never hairy or scaly; proboscis absent and replaced by chewing mouthparts…..49

46. 49a(48b) – Pronotum usually smaller than mesonotum….50
49b - Pronotum lager than mesonotum, may be very broad and partly of completely covering head, curved and sometimes pointed, or very long and slender…..52

47. 50a(49a) – Usually very elongated, slender, and stick like body…
50a(49a) – Usually very elongated, slender, and stick like body….Phasmida
50b – Not as above

48. 51a(50b) – Tarsi 4 segmented; prothorax narrower than head; tip of abdomen without long tails although short stubs may occur…..Isoptera (in part)
51b - Tarsi 5 segmented; prothorax as wide or wider than head; tip of abdomen with 2 long tails; uncommon…..Grylloblattodea

49. 52a(49a) – Femora of hind legs thickened for jumping…
52a(49a) – Femora of hind legs thickened for jumping….Orthoptera (in part)
52b - Femora of hind legs not thickened…53

50. 53a(52b) – Body flatten or front legs thickened, spined, and used for grasping…Dictyoptera (in part)
53b – Body cylindrical and not flattened; front legs not thickened or spiny…..Orthoptera (in part)