32 MISC. PUB. 601, U. S. DEPT. OF AGRICULTURE 



ODONATA 



Odonata (dragonflies, damselflies) are large insects with two pairs 

 of membranous, many-veined wings, the hind pair as large as or 

 larger than the front pair. The mouth parts are formed for chewing. 

 The immature stages are aquatic and unlike the adults. They are 

 common around ponds, lakes, and streams. Both the adults and the 

 immature stages feed on other insects, and because they feed at least 

 to some extent on mosquitoes and other small flies they are beneficial. 



PSOCOPTERA 



Psocoptera (psocids or booklice) are small, either winged or wing- 

 less ; the winged members have two pairs of wings with a few, mostly 

 crooked, veins. The antennae are long; the mouth parts are formed 

 for chewing. The immature stages resemble the adults. These insects 

 are common around old paper and books and are found out of doors 

 on trunks and leaves of trees, or on stones or other places where lichens 

 and fungi grow. They are gregarious and feed upon lichens and vege- 

 table matter. Some of the species are annoying household pests. ( See 

 fig. 23.) 



Figure 23. — Psocoptera. The booklouse (Liposcelis divinitorius (Mull.)), a com- 

 mon species. Actual length about 1 mm. 



MALLOPHAGA 



Mallophaga (biting lice or bird lice) are small, flat, wingless, para- 

 sitic insects with mouth parts formed for chewing. The legs and 

 antennae are short. The immature stages resemble the adults. These 

 insects feed upon feathers of birds or on hair and skin scales of other 

 animals. They are frequently important pests of domestic fowls and 

 animals. 



ANOPLURA 



Anoplura (true lice or sucking lice) are small, flat, wingless, para- 

 sitic insects with mouth parts formed for piercing and sucking. The 

 legs and antennae are short. The immature stages resemble the adults. 



