74 



OHIO EXPERIMENT STATION: BULLETIN 356 



Description of Mite. — The mites although small — the male 

 may attain a length of one-fortieth of an inch, the female one- 

 thirty-fifth of an inch — are readily visible to the naked eye of an 

 experienced observer. They may be found on any part of the body 

 covered by the wool, but are most commonly found where the wool 

 is thickest. According to Gerlach, the female deposits its eggs in 

 clumps of the skin at the base of the wool fibers. Each female gen- 

 erally deposits not less than fifteen eggs, which hatch after an in- 

 cubation of 3 or 4 days. The young mites grow to maturity in 7 or 

 8 days and in 3 or 4 days more mate and start the cycle over again. 



A more advanced case of common scab. 

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



Control. — Certain points in the life history of the scab mite 

 have an important bearing upon the method of combating this par- 

 asite. The complete destruction of the scab mites is necessary in 

 order to cure the disease that they produce. The eggs of the scab 

 mite seem to be especially tenacious. It is, therefore, necessary to 

 dip a second time after the eggs have hatched, but before the young 

 have become sufficiently mature to deposit eggs again. From the 

 data on the life history, 10 to 14 days after the first dipping has 

 been determined as the best time for the second dipping. 



The vitality of the scab mite when separated from the host 

 animal is also of practical importance. Since the mites and eggs 

 may be scattered here and there in sheds, or pastures, on tags of 

 wool and loosened scabs, it is necessary to know how long they will 



