POULTRY DlSIiASES AND THEIR TREATMENT. 



133 



of i,M-eat cconiiinio iniportaiicc. Occasionally one or another of 

 the other species heconies sufficiently ahnndant to be of local 

 importance. The mites are small 8-legged animals related to 

 the si)iders. Some of the mites parasitic on the fowl visit their 

 host only to feed, as the common red mite; others remain on the 

 surface of tlu- skin or on tlie feathers, as in the case of deplum- 

 ing scabies. Others live under the skin, causing deep-seated 

 skin diseases like scaly leg; still others find their way into the 

 internal regions of the l:)ody, living either on mucous membranes 

 like the air sac mite (p. no) or upon the connective tissue like 

 the connecti\'e tissue mite. 





/r 





Fig. 28. The common "red mite" of poultry, Dcvmany- 

 ssus gallinac, a, adult, d and e, young. (After 

 Osborn). 



The most common and mo.sl injurious mite j)arasitic on fowls 

 is the common fowl mite or red mite, Dermanyssus gallina:. 

 The.se mites are ])resent in almost every poultry house that is not 

 kept very clean. When they are present in large numbers they 

 arc a seri(-)Us pe^t. Tlu'^ mite is a little more than ' j millimeter 

 long. 'I'Ik' female is a little larger than ilic male. When empty 

 Ihey are gray with dark .spots, hut usually they appear some 

 shade from yellow to dark red according to the amount of fowl's 

 blood they contain. They visit the fowls only to feed and spend 

 the rest ot the time on tlic under sides of the roosts, in cracks 

 and crevices, under collections of droppings or other filth and 

 in the nesting material, especially if .'^uch material is dirty straw. 

 The mites breed in these places. They reproduce very rapidly, 

 especiall}- in spring and smnmer. The eggs are laid in con- 



