Mites Injurious to Domestic Animals. 83 



pustules. The parasites are only found in places where the skin 

 is fine in texture. The disease usually spreads from the snout, 

 over the neck, the under part of the chest and abdomen, and over 

 the flanks and inner parts of the legs. Some of the pustules are 

 embedded deeply in the skin. In the pig, demodectic mange spreads 

 very slowly, and only a few animalsi n the herd are infected. 

 Usually the general health of the animals is not affected. 



FIG. 71. 



Laelaps echidninus (p. 91). A widely distributed parasite of the brown 



rat. Female, from below, x 66. (a) Chelicera. 



(After Hirst, Bull. Ent. Res. 1913.) 



Demodex bovis, Stiles, 1892. 



(Fig. 51.) 



A fairly wide species, the female being usually from three to 

 three and a half times as long as wide. Abdomen distinctly pointed 

 at the end, especially in the male. 



The demodectic mange of cattle Ms been reported from Nyasa- 

 land and the Belgian Congo. Nodules or pustules varying in size 

 from the head of a pin to that of a fowl's egg are present on the 

 skin, occurring principally round the ears, on the sides, shoulders, 



G 2 



