SOME PESTS OF OHIO SHEEP 



73 



are formed. As the mites multiply the area of the infested regions 

 increases and the itching becomes more and more aggravating. 

 The pimples break and serum oozes to the surface of the skin. 

 This material becomes mixed with the natural secretions and dirt 

 and soon hardens into crusts or scabs. The skin in the infested 

 areas becomes hard and thick. This may be readily detected by 

 pinching up a portion and comparing it with the surrounding 

 healthy skin. Constant biting, rubbing and scratching of the in- 

 fested region soon causes the fleece to assume a condition commonly 

 known as "broken". It becomes discolored, worn and ragged. 

 Large areas of the skin become entirely denuded of wool as shown 

 on page 74. Unless properly treated the disease may spread over 

 the entire body, the sheep becoming more and more debilitated 

 until it finally succumbs. Only a few have been known to recover 

 spontaneously. 



A slightly advanced case of common scab. 

 From Bui. No. 21, Bureau of Animal Industry, U. S. D. A. 



