44 



POULTRY DISEASES 



knows has not been reported in this country. It 

 affects the body of both chickens and pigeons. 

 The one on chickens is the Sarcoptes laevei va- 

 riety goMince and the one on. pigeons is the Sar- 

 coptes laevei variety columhcB. 



The ascarids parasitic for birds are placed un- 

 der the following genera: sarcoptes, cytodites, 

 trombidium and dermanyssus. Unlike the various 

 genera of lice the scab parasites differ greatly in 

 the effects which they produce and therefore a 

 separate discussion of each one will be given. 



Scaly Legs— Scabies of the Legs 



This condition is very common; it constitutes 

 leg scabies, and is caused by a parasite called the 

 Sarcoptes mutans variety gallincB. 



Sarcoptes Mutans 



Description.^This parasite is one of the same family of 

 scab parasites that infest horses, cattle, hogs, sheep and cats. 

 That particular branch of the family af- 

 fecting chickens is distinguished by call- 

 ing it "variety gallinae"; gallinse being a 

 Latin word meaning "of the chicken." 

 Owing to the small size of the parasile, it 

 is often called a mite. Fig. 10 illustrates 

 the parasite magnified 100 times; the 

 actual size of the parasite is shown by the 

 smalL dot in the square at the right side 

 of the drawing. In the drawing it will 

 be noted that the legs are short and 

 strong and that its mouth parts are 

 arranged for biting the skin. They sub- 

 sist upon serum that exudes at the point 

 of attack and forms scales or scabs (see 

 Fig. 11). 



Life History. — The female lays her 

 eggs under the scabs, where in about ten 

 days they hatch, if conditions are favor- 

 able. The larvae or young mites are 

 provided with only three pairs of legs 

 and are not provided with sexual organs. 

 They pass through several molts and are finally developed 

 into the adult stage, and at that time are provided with four 

 pairs of legs, with genital organs and are sexually mature. 



Fig, 10. Sarcoptes 



Mutans Variety 



Gallant 



A, Mouth parts. B, 

 short, stubby legs. 

 C, dot indicating 

 actual size of para- 

 site. 



