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OHIO EXPERIMENT STATION: BULLETIN 356 



the ground, on their fore legs or against other sheep. The small 

 pimples break and a watery fluid runs out which on drying forms a 

 small crust. Repeated scratching aids in spreading the infection 

 and increasing the inflamation. The little brownish-yellow scabs in 

 time become larger, thicker and may even cover the entire face if 

 treatment is not applied. 





A shorn sheep with large bare area due to scab. 

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



Description of mites. — All stages of this parasite, eggs, young 

 and adult males and females, may be found in the moist layer 

 underneath the scabs. The adults are just visible to the naked eye 

 of the trained observer, being about 220 to 440 micromillimeters 

 long. The minute, oval egg is deposited by the female in the bur- 

 rows which she makes by means of her mandibles. One female as 

 she progresses in her burrow may leave behind her a row of from 

 10 to 40 eggs. The young, on hatching, spread to healthy tissue, 

 beginning burrows of their own. Thus the mites spread the infes- 

 tation over the face and to other sheep, should the infested sheep 

 come in contact with healthy animals. This mite has been known 



