Mites Injurious to Domestic Animals. 17 



(with the exception of Psoroptes natalensis) should be regarded 

 merely as races or slight varieties of a single species. 



The hairs on the abdominal lobes of the male are all normal in 

 appearance in P. communis (fig. 3 a-g, i), none of them being in the 

 least flattened or blade-like. 



Although differing so little in structure, various observers have 



FIG. 3. 



Posterior abdominal lobes of males of Psoroptes. (a) Psoroptes 

 communis, var. equi ; (b) var. ovis, (c) var. cuniculi, (d) var. bovis 

 (from Johannesburg, South Africa) ; (e) var. caprae (St. 

 Vincent, West Indies) ; (f) var. bovis (from Amarillo, Texas) ; 

 (g) and (i) var. cervinae (Colorado) ; (h) Psoroptes natalensis, 

 Hirst. (After Hirst, Journ. Quekett Microscopical Club, (2) xiv, 

 Nov. 1921.) 



pointed out that it is very difficult to transmit mites of the genus 

 Psoroptes from one host to another of a different species. For 

 instance, Delafond and Bourguignon failed to transmit Psoroptes 

 communis, var. ovis, to any other host. 



Psoroptes communis occurs' on the following domestic animals : 

 sheep, goats, cattle, horses and rabbits. 



Scab or Psoroptic Mange in Sheep. The variety found 



c 



