External Parasites 



207 



closely resembles M. pallidum, is also sometimes found. 



These are active lice living on all parts of the body. They 



often crawl on to the hands when handling 



or plucking birds, and may sometimes be 



found in the nests. 



There are several other lice which some- 

 times infest poultry. Each of these species 



is confined to a special region of the host. 



Although capable of crawling about, the lice 



of these species for the most part remain 



nearly stationary, often with their heads 



buried in the skin and their bodies erect. 



Two species, Lipeurus variabilis and Lipeii- 



rus heterographus, live among the barbs of 



the wing and tail feathers. Goniodes dis- 



similis is found under the wings and on the 



rump. The appearance of two of the species 

 mentioned, viz., Lipeib- 

 rus variabilis and Goni- 

 odes dissimilis, is shown in Figs. 37 

 and 38 respectively. 



All true bird lice {Mallophaga) have 

 biting, not piercing mouth parts. They 

 live upon fragments of feathers, scales 

 of the skin and other such debris. It 

 is evident from the action of infested 

 birds that these parasites cause con- 

 siderable pain and itching. This must 

 be particularly true when they are 

 present in large numbers. 



Life-history of Lice. — All the lice 

 breed fairly rapidly. The eggs or nits 



are laid upon the down feathers, as a rule ; they are often 



beautifully sculptured objects, oval in form. In about 6 



Fig. 37. — Lipeu- 

 rus variabilis. 

 A louse that 

 infests poul- 

 try. Much en- 

 larged. (From 

 Banks, after 

 Denny.) 



Fig. 38. — Goniodes dis- 

 similis, a louse that 

 infests poultry. Much 

 enlarged. (From 

 Banks, after Denny.) 



