Scabies of Fowls. 



965 



To insure success disinfection of tlio fowl houses and 

 jjerches is necessary. 



2. Mange of Feathered Parts of the Body. ( Scabies dephi- 

 mans.) This form of scab is caused by the Knemidocoptes 

 (Sarcoptes) laevis. 



The Knemidocoptes Isevis which has been called Sarcoptes leevis by Eailliet is 

 very similar to the Knemidocoptes mutans, from which it differs in that the female 

 possesses no shield-like chitinous formations on the back, the U-shaped chitinous 

 structure is less developed, the body more circular and the hind pair of legs pro- 

 ject over the edge of the body. The differences in sizes between these two kinds 

 of mites are inconstant, as the authors had an opportunity of ascertaining. 



The Knemidocoptes Iscvis columbas, the Kn. leevis gallinse, Kn. laevis phasiaui 

 are only subdivisions of the Knemidocoptes laevis. 



Fig. 150. Foot mange in the fowl. 



Tliis form of mange occurs in chickens, sometimes as an 

 enzootic, also in j)igeons and exceptionally in pheasants. It 

 occurs particularly in spring and summer, and disappears al- 

 most completely with the approach of autumn, but reappears 

 the following spring. It usually begins in the sacral region 

 and then passes on to the back, the abdomen, the thighs, the 

 neck and the head. Frequently, however, the head or the upper 

 part of the neck may be first attacked (Fig. 151). Contagion 

 seems to spread chiefly by treading, consequently the loin re- 



