Class tnsecta 539 



Order 9. Thysanoptera (Thrips). Elongate, small forms, many wingless, 

 others with short wings or well-developed ones. Mouth parts fit 

 together to form a cone. Other parts form a needlelike stylet. Of 

 economic importance due to their destruction of leaves and flowers. 

 About 3,000 described species, with possibly an equal number of 

 undescribed forms. 

 Order 10. Anoplura (Sucking Lice). Flattened, wingless, sluggish in- 

 sects. Mouth parts modified forming a retractile, piercing-sucking 

 structure. Short antennae. This group includes the crab louse, 

 body louse or cootie, and the true lice. Of great economic importance 

 due to transmission of diseases such as typhus fever, trench fever, 

 relapsing fever. One form is able to transmit tularemia from rabbits 

 to man. The social significance of this order has been explored in 

 literature. About 250 species. 

 Order 11. Hemiptera (True Bugs). Recognizable by basal portion of 

 front wing being hard, mouth parts in form of beak. About 55,0(X) 

 known species. 



Suborder Heteroptera (Water Boatmen, Backswimmers, Giant 

 Water Bugs, Bedbugs, Plant Bugs, Chinch Bugs, Stink Bugs). 

 Forms varying in size from small to large. Nymphs similar in 

 appearance to adults. Many of great economic importance due 

 to destruction of food crops; others such as bedbugs may be 

 pests in dwellings, while still another predatory species is an 

 important natural enemy of the Colorado potato beetle. 

 Suborder Homoptera (Cicadas, Leaf Hoppers, Aphids, Scale In- 

 sects, etc.). Many of great economic importance due to de- 

 struction of food plants. 

 Series Holometabola. Forms having a complete metamorphosis: egg, 



larva, pupa, and adult in life history. 

 Order L Neuroptera (Lacewings, Ant Lions, Mantispids). Adults very 

 small, usually having two pairs of clear wings, larvae most often 

 terrestrial and predaceous. About 4.000 species. 

 Order 2. Megaloptera (Dobson Flies and Alder Flies). Large insects 

 with aquatic larvae and terrestrial pupae. With long antennae, chew- 

 ing mouth parts, large eyes, two pairs of wings which are of similar 

 texture. Larvae predaceous, known as hellgrammites, used for fish 

 bait. About 500 species. 

 Order 3. Hymcnoptera (Sawflies, Ichneumons, Ants, Bees, and Wasps). 

 Mouth parts of chewing type or modified for lapping or sucking. 

 Base of abdomen usually constricted. A very large group with many 

 varied forms. Many such as the bees and ants with social organization 

 and castes. Of great economic importance: bees for production of 

 honey and pollination of plants, parasitic forms for destruction of 

 other insects. At least 120,000 species, with many small parasitic 

 forms which are undescribed. 

 Order 4. Coleoptera (Beetles and Weevils). Aduhs usually with two 

 pairs of wings. The first pair is hard, shell-like, and folded over the 



