410 THE MANAGEMENT AND FEEDING OF CATTLE 



comes from those of the class mentioned second. The 

 sarcoptes burrow channels and live in or beneath the 

 cuticle. The psoroptcs live on the surface of the skin 

 and move about freely over it. The symbiotes affect 

 parts near the feet. The psoroptes increase very rapidly. 

 They produce a scurfy and scabby condition of the skin, 

 and it is under these scabs that they live and multiply. 

 The infestation of cattle is far more common on the 

 western ranges than elsewhere. On these it is com- 

 monly referred to as Texas or range itch. During re- 

 cent years, largely through the influence of contamina- 

 tion from cattle exhibited at the live stock fairs, this 

 trouble has come to be present in an annoying degree in 

 many of the most valuable of the pure-bred herds. For- 

 tunately each class of live stock is infested by mites only 

 which do not flourish on the others, notwithstanding the 

 similarity of the results which they produce. Mites are 

 so minute that their presence cannot, in all instances, 

 be detected without the aid of a lens. 



The cattle mite psoroptes usually begins its attacks 

 on the parts around the top of the shoulder and the root 

 of the tail. It gradually spreads along the back, sides, 

 and down on the outer portion of the legs, but is seldom 

 or never found on the inside of the legs, thighs, or 

 abdomen. From the irritation of the skin, pimples are 

 formed, which develop into vesicles filled with a fluid 

 and from these comes a gummy exudation which forms 

 a thick crust. The hairs for a long time stand up 

 through these crusts, but finally fall off, leaving bare 

 patches of calloused and wrinkled skin. The mites soon 

 abandon the bare parts and begin work in parts ad- 

 jacent to them. The trouble is communicated by con- 

 tact with affected animals or with surfaces against which 

 they may have recently rubbed. Mange in cattle is 

 much less prevalent in summer than in winter. 



The most prominent indications of cattle scab 

 mites are the staring condition of the coat on the 



