PARASITISM 



329 



FIG. 369. Bed bug. Side view shows 

 the piercing beak. Photograph twice 

 life size. 



living on birds and mammals, differ from the true mites 

 and ticks in having only three pairs of legs, and the body 

 is divided into three parts characteristic of all insects. 

 Because of their parasitic habits the wings have been lost. 

 They secure their food by sucking the blood or by feeding 

 on the hair and feathers. 

 Only three species affect 

 man. 



The bedbug and many 

 of the flies are what may 

 be termed temporary para- 

 sites as they are present 

 on the host only at inter- 

 vals. Among the fleas, 

 Pulex irritans is the one 

 annoying the dog, cat, and man. The eggs are often 

 laid on the hair of the cat or dog and the slender wrig- 

 gling larvae live in the 

 dirt filling the cracks 

 of the floor or similar 

 places. The female of 

 several species of mos- 

 quitoes attacks all warm- 

 blooded animals and 

 often conveys to man 

 serious diseases, such as 

 malaria, filariosis and 

 yellow fever. 



Many insects are parasitic during their larval life, but 

 independent during the adult stage. The larvae of several 

 species of botflies dwell during the larval state either in 



FIG. 370. Cat and dog flea enlarged fifteen 

 tim es . After Howard. 



