|MadSci Network: General Biology|
According to Borror, Triplehorn and Johnson (1989) there are 31 orders of Hexapods, of which 28 are considered true insects. Of these the thirteen (actually fourteen) largest are (in order) Coleoptera or beetles- including weevils (300,000 world species as of 1952 and probably in reality over a million), Diptera or flies - including mosquitoes, gnats, and any other two-winged insects except for male scale insects and twisted- winged parasites, which belong to different orders (120,000 species as of 1952), Lepidoptera or butterflies, moths and skippers (112,000 species as of 1952), Hymenoptera or sawflies, parasitoids, ants, bees and wasps (108,000 species as of 1952), Hemiptera or true bugs (50,000 species as of 1952), Homoptera or cicadas, hoppers, aphids and scale insects (32,000 species as of 1952), Orthoptera or grasshoppers, crickets and katydids (12,500 species as of 1952- note: in modern classification systems this order does not include mantids, walkingsticks or cockroaches), Trichoptera or caddisflies (7,000 species as of 1952), Collembola or springtails (6,000 species as of 1952- note: these are considered Hexapods, but not true insects by Borror, Triplehorn and Johnson), Phthiraptera or lice (5,500 species as of 1952- note: these are often separated into Anoplura and Malophaga or sucking and biting lice, respectively), Odonata or dragonflies and damselflies (4,870 species as of 1952), Neuroptera or net- winged insects (4,670 species as of 1952), Thysanoptera or thrips (4,000 species as of 1952), and Blattaria (4,000 species as of 1952). Reference: Borror, D. J., C. A. Triplehorn and N. F. Johnson. 1989. An introduction to the study of insects, 6th ed. Saunders College Pub. Ft. Worth.
Try the links in the MadSci Library for more information on General Biology.