Mites Injurious to Domestic Animals. 81 



short ; the hair on the spots is very thin, but not entirely absent. 

 This disease usually commences on the saddle or neck of the animal. 

 It does not appear to be at all infectious. The disease may also 

 occur in a pustular form. The Demodex of the horse is often found 

 in skin complaints due to other causes, especially in sarcoptic 

 mange. 



Williamson and Oxspring (Vet. Journ., Ixxvi, p. 376, 1920) 



FIG. 



(a) Liponyssus bursa (p. 89), <5 , from below, x 92. 



(After Hirst, Bull. Ent. Res. 1915.) 

 (b) L. sylviarum (p. 90), S , from below, x 110. (Original.) 



state that in no case does demodectic mange of the horse show such 

 marked symptoms as are commonly met with in the dog, but the 

 majority of cases show obvious lesions which one would be far from 

 justified in neglecting. There seem to be two stages in the disease. 

 In the first stage, which includes the most benign and usually the 

 more recently infected cases, there is no pustular formation, but 

 there is always very strong pruritus. Certain areas of the skin 

 are more irritable than others ; these are generally on the neck, 



G 



