SEGMENTED SCHIZOCOELS 



247 



sites of birds and mammals, feeding upon hair, feath- 

 ers, and skin, not known to infest man (Figure 14.23). 



thereby reducing plant vigor and introducing disease 

 (Figure 14.25). 



ORDER ANOPLEURA (Sucking Lice) 



Diagnosis: small, to about about 1/4 inch long; 

 wingless, body flat, mouth parts piercing and sucking; 

 eyes reduced or none; no true metamorphosis; ex- 

 ternal parasites on mammal blood and transmit 

 various diseases including typhus and trench fevers; 

 includes the human louse, or "cootie" (Figure 14.24). 



ORDER HOMOPTERA (Cicadas, Hopper$, Scale 

 Insecis, eic.) 



Diagnosis: mostly small; cicadas to about two 

 inches long; wingless or four wings, membranous 

 and of like texture throughout, roofed over abdomen 

 at rest; mouth parts piercing and sucking; herbivo- 

 rous; many are serious pests and a few transmit di- 

 seases (Figure 14.26). 



Figure 14.24 Anopleura, a sucking louse (x 5), to the left; and 

 Thysonopetero, a thrip (x 6), to the right. {After various sources.) 



ORDER THYSANOPTERA (Thrips) 



Diagnosis: minute to small (to 1/5 inch) and 

 slender; wings four, alike and heavily fringed by hairs 

 or wingless; mouth parts conical, rasping and suck- 

 ing; commonly parthenogenetic; mainly plant feed- 

 ers, destroying many plants by feeding or introducing 

 disease; some predaceous on small arthropods, a few 

 attack man (Figure 14.24). 



ORDER HEMIPTERA (Bugs) 



Diagnosis: mostly large; wingless or four wings, 

 front wings thick with horny bases and otherwise 

 membranous, crossed at rest; hind wings mem- 

 branous and folding under forewings; mouth parts 

 piercing and sucking; a large group of common fresh- 

 water and terrestrial insects; some are beneficial 

 predators on harmful insects, some are definitely 

 harmful; some are blood-sucking, carrying diseases 

 of man and other animals; many suck plant juices. 



ORDER EPHEMEROPJERA (Mayflies) 



Diagnosis: one inch long; four membranous 

 wings, front wings much larger, all held up at rest; 

 chewing mouth parts, but much reduced; up to 21 

 molts and three years as fresh-water nymphs, a few 

 hours or days as an adult; nymph herbivorous, adults 

 do not feed; prey of aquatic insects and vertebrates, 

 hence fishing "flies" or lures are patterned after may- 

 flies (Figure 14.27). 



ORDER ODONATA (Damselflies and Dragonflies) 



Diagnosis: large, to over three inches long; four 

 wings, transparent and membranous, held vertically 

 (damselflies) or laterally (dragonflies) at rest; chew- 

 ing mouth parts, tooth-like; nymphs aquatic, feeding 

 on mosquito larvae to small fish; adults terrestrial, 

 feeding on other insects (Figure 14.27). 



Subclass PTERYGOTA: Division Endopterygota 



Diagnosis: Division Endopterygota metamorpho- 

 sis complete, young stages are larvae without com- 

 pound eyes; wings develop internally. 



ORDER NEUROPTERA (Nerve-winged Insecfs) 



Diagnosis: small to large, to about three inches 

 long but most shorter; four wings, alike and mem- 

 branous, with many cross veins, roof the abdomen at 

 rest; chewing mouth parts; fresh-water or terrestrial; 

 both larvae and adults are insect predators; also 

 preyed upon, especially by fish, hence a group copied 

 as fishing "flies" (Figure 14.28). 



