19 



that ouh" eiables llioin to bite. Tliey live on the 

 crusts, scales and dead cells that gather on the surface 

 of the skin and that are prevented from falling off by 

 the featliiers. 



There are several vai'ieties of lice belonging to four 

 principal genera: these are Goniodes, Goniocotes, Lip- 

 eurus and Menopen. While these parasites differ eon; 

 siderably as regards their shape and size they resem- 

 ble each other very closely in their habits. All of 

 them are very small insects, from 1-100 to Id incli 

 l&ng and their bodies are plainly divided into three 

 I)arts; the head is very large and fiat, the thorax, or 

 second segment, is roundish and considerably smaller 

 than the head ; the abdomen, oi 

 most posterior segment, is long, 

 oval and plump. Their color 

 is usually grayish or yellowish, 

 but some of them show differ- 

 <?rit shades of brown. Although 

 these parasites do not pene- 

 trate the skin and suck the 

 blood as fleas do, and as the 

 lice of mammals do, they cause 

 a gieat deal of itching and an- 

 noyance while ci'awling about 

 over the sui-faee and sometimes chicken louse. 



they bite the skin and in that Goniode><disximiu.% m&ie. 



, . . , _ One ol' the most common va- 



way occasion mi.eh irritation, neties. 20 times natural size. 



At one time it was thought that lice were bred by 

 filth and that tbey generated themselves, as it were, 

 in dirty places, but it has been shown that this is not 

 the case and that they are only produced by like para- 

 sites and luive the property of reproducing themselves 



