Mites Injurious to Domestic Animals. 21 



and sulphur dip, which, if properly used, and at the right strength, 

 destroys the eggs as well as the mites. 



Shilston was unable to infect goats by placing all stages from 

 scabby sheep into their ears, for the mites did not live more than 

 two days. Specimens of sheep Psoroftes were placed by him on 

 goats, and other goats were kept in contact with scabby sheep for 

 several months, but with negative results. Similarly, all attempts 

 to produce otacariasis in rabbits, by infecting them with Psoroptes 

 Gomnmnis, var. ovis, were unsuccessful. 



Psoroptic Mange or Parasitic Otitia of the Goat.— 



Psoroj)tes commuids, var. cajjrae, like the variety found in rabbits, 

 is confined to the ears of its host. Usually the presence of the mites 

 does not seem to be harmful, but occasionally it provokes serious 

 trouble, inducing deafness and lack of appetite, and sometimes 

 causing the death of the infected goats. 



Shilston found that P. communis, var. cajirae, was able to live 

 and reproduce itself on sheep, but the second generation usually 

 died on reaching the nymphal stage, and in no case was a third 

 generation observed. 



Otacariasis of the Rabbit. — The Psoroptes of the rabbit 

 (P. communis, var. cuniculi) usually occurs only in the ear, numerous 

 specimens being found in a yellowish substance which may fill up 

 almost the entire cavity. Cases have been recorded in which the 

 face, neck and limbs were also attacked, but they seem to be rare. 

 Sometimes the body is afiected with a combination of psoroptic 

 and sarcoptic mange. 



This variety of Psoroptes is quite a common parasite of English 

 rabbits, and also occurs on the Continent, in North America, and 

 in several parts of Africa. 



P communis, YSkX. cujm'cmK, can apparently be transmitted to the 

 horse, and, according to Shilston, it is able to live on sheep for 

 periods up to seventeen days ; during that time it may lay eggs 

 and give rise to symptoms and lesions similar to those due to the 

 sheep Psoroptes. The second generation, however, die before repro- 

 ducing, and therefore continuous acariasis in sheep cannot result 

 from infection with rabbit Psoroptes. 



Psoroptic Mange in Cattle.— In cattle psoroptic mange 

 commences at the base of the tail, or on the neck or withers, 

 and gradually extends to neighbouring parts of the body ; it 

 is rarely present in a generalised form. In summer this kind^of 



