6 FARMERS BULLETIN 713. 



ifest by a reddening of the skin. This stage of the disease is rarely 

 if ever detected b^^ casual observation. (See fig. 3.) As the mites 

 multiply, large numbers of small wounds are made in the skin and 

 are followed by intense itching, with formation of papules, inflam- 

 mation, and exudation of serum. The serum, which oozes to the 

 surface, becomes mixed with the natural excretions and particles of 

 dirt, and more or less infested with microorganisms. This mass soon 

 hardens into crusts or scabs in the wool ; these in the early stages are 

 of a yellowish color, but as the disease advances and the scabs thicken 

 they become dark from blood stains, dirt, and other causes. When 

 the disease begins only a small pimple can be seen, but as the mites 



multiply they seek the healthier parts around the edges of the 

 diseased area, and thus the lesion or scab is continuously enlarged. 

 The areas of the skin affected become hardened and thickened. This 

 is readily detected by pinching up a portion and comparing it with 

 the surrounding healthy skin. Other conditions resembling scab 

 rarely if ever cause this characteristic, uniform thickening of the 

 skin. AVhen the affected skin is pinched or handled, the sheep as a 

 rule turns its head toward the lesion, thrusts out the tongue, licks 

 the lips, and champs the jaws. 



The intense itching causes the sheep to become restless. This 

 irritation is particularly noticeable after the animals have been 



