Classification of Insects

Insects form the class Insecta of the phylum Arthropoda. Insects are divided into orders based on wing structure, mouth parts, and metamorphosis. Entomologists do not agree on the number of orders or their names. Most, however, divide insects into the 31 orders listed below. The orders are usually arranged with the most primitive insects first. Orders 1 through 4 do not undergo metamorphosis; 5 through 21 undergo incomplete metamorphosis; and 22 through 30 undergo complete metamorphosis.

1. Protura. Tiny; wingless; no eyes or antennae. An example is the proturan.

2. Diplura. Wingless; two long tail-like cerci. An example is the japygid.

3. Thysanura. Wingless; three long tail-like cerci.

4. Collembola. Tiny; wingless; tail-like appendage permits them to spring suddenly. An example is the springtail.

5. Grylloblattodea. Wingless; small eyes (or none); chewing mouthparts. Called cricket-cockroaches.

6. Orthoptera. Leathery forewings; large membranous hindwings (or none); chewing mouthparts. Most have long, muscular hindlegs for jumping.

7. Phasmatodea. Some wingless; others have large, colorful wings; chewing mouthparts. Bodies resemble twigs or leaves.

8. Dictyoptera. Leathery forewings; large membranous hindwings (or none); chewing mouthparts; triangular, downward-facing head.

9. Mantophasmatodea. Wingless; chewing mouthparts; long, straight body; downward-facing head; hook-like feet.

10. Dermaptera. Small leathery forewings; large membranous hindwings (or none). Chewing mouth-parts.

11. Plecoptera. Large, membranous wings; chewing mouthparts; soft body. The nymphs are aquatic.

12. Ephemeroptera. Membranous wings; no mouth-parts; soft body; two or three long tail-like projections. Aquatic nymphs.

13. Odonata. Large, glassy, membranous wings; chewing mouthparts. Aquatic nymphs.

14. Isoptera. Social insects living in large nests. Physical structure varies according to the role played by the individual in the caste system. Chewing mouthparts; soft body.

15. Embioptera. Males have narrow, membranous, brown wings; chewing mouthparts. Spin silken webs from glands on the forelegs. An example is the web-spinner.

16. Psocoptera. Typically four narrow, membranous wings held over the abdomen when at rest; chewing mouthparts. An example is the book louse.

17. Zoraptera. Typically four narrow, membranous wings shed at maturity; chewing mouthparts. Inhabit rotten wood and live in colonies. An example is the zorapteran.

18. Mallophaga. Wingless; chewing mouthparts; small, flat body, eyes reduced. Parasites of birds and mammals.

19. Anoplura. Similar to order Mallophaga, except with sucking mouthparts. Feed only on the blood of mammals.

20. Thysanoptera. Long hair fringes on narrow wings; sucking mouthparts. Spread viral plant diseases. An example is the gladiolus thrips.

21. Hemiptera. Forewings thick at the base and membranous at the tip. Sucking mouthparts. Many are plant pests that transmit disease; some are bloodsuckers.

22. Homoptera. Thickened, membranous wings; piercing-sucking mouthparts. All are plant eaters.

23. Neuroptera. Net-veined wings; chewing mouthparts; soft body. Both aquatic and terrestrial.

24. Coleoptera. Forewings hard, meeting in a straight line down the back; hindwings membranous; chewing mouthparts. This is the largest order of insects.

25. Strepsiptera. Females are saclike parasites within other insects. Males have tiny forewings; large membranous hindwings; chewing mouthparts. An example is the stylops.

26. Mecoptera. Long, narrow wings; chewing mouthparts; head lengthened to form a beak. In males, the tip of the abdomen may be turned up. An example is the scorpion fly.

27. Trichoptera. Long, hairy wings; chewing mouthparts. Aquatic larvae build stone cases.

28. Lepidoptera. Wings covered with scales, often colored; sucking mouthparts.

29. Diptera. Typically two membranous wings and two knoblike halteres. Sucking mouthparts.

30. Siphonaptera. Small; sides of body flattened; sucking mouthparts. All adults feed on the blood of mammals.

31. Hymenoptera. Smaller hindwings; chewing or sucking mouthparts; many with constricted waist.

Includes the social insects, except the termites.