Economic Importance of Animals 551 



although many of the mosquitoes are active after dark. The adults and 

 larvae of dragonflies and damselflies (Fig. 277) serve as food for aquatic 

 and terrestrial animals. 



Order 5 — Plecoptera: The stonefly larvae (Fig. 278) live in running 

 water under stones and serve as food for fish and other aquatic animals. 



Order 6 — Mallophaga: The biting bird lice (Fig. 279) eat the hair, 

 epidermal scales, and feathers of mammals and birds. Their sharp 

 claws produce irritations and bleeding which causes the host much an- 

 noyance and may even lead to infections. Birds often resort to dust 

 baths in their attempt to combat the lice. 



r.' 



\ 



X 



Fig. 273. 



Fig. 274. 



Fig. 273. — Silverfish or fish moth {Lepisma saccharina) of the order Thysanura. 

 Dorsal view and much enlarged. (From Back: Silverfish, U. S. Department of 

 Agriculture, courtesy of Department of Entomology and Plant Quarantine.) 



Fig. 274. — Springtail {Isotomurus palusiris) of the order Collemhola (much en- 

 larged). (From Folsom: Nearctic Collemhola or Springtails, of the Family Isoto- 

 midae, U. S. National Museum, Smithsonian Institution.) 



