THE MORE COMMON AILMENTS OF SHEEP 389 



soften the scabs with some kind of oil or grease and then 

 to remove them with soap and water. 



The mite, Chorioptes communis, occurs so rarely that 

 it is scarcely necessary to discuss it. It may be said, 

 however, that it usually begins on the feet and extends 

 upwards. The skin when attacked shows an inflamed 

 condition followed by free scaling of the same, and this 

 in turn is followed by the forming of yellowish-colored 

 crusts, beneath which the parasites congregate. For- 

 tunately this trouble is not readily communicated to other 

 sheep, and it may be treated in the same way as Sarcoptes 

 scabiei, referred to in the preceding paragraph. 



The mite, Psoroptes communis, is by far the most 

 troublesome and harmful of all the external parasites 

 which prey upon sheep. The trouble resulting is now 

 more commonly referred to as body scab. So great has 

 been the loss resulting from its presence that legislation 

 has been enacted in many countries with a view to pre- 

 vent its spread and in the hope of ultimately bringing 

 about its eradication. Although it infests goats, com- 

 munication usually comes from other sheep or from the 

 quarters which they have inhabited or visited not long 

 previously. 



This mite, though small, is visible to the naked eye. 

 The life history of all these mites is very similar. They 

 attack the external skin by biting it in search of food. 

 Scabs quickly form as the result of the irritation that fol- 

 lows. This irritation is thought to be, in part at least, 

 the outcome of a poisonous fluid which accompanies the 

 bite. Under the scabs the mites lay their eggs. These 

 eggs hatch in 2 to 3 days, and the mites reach the adult 

 stage in about 15 days. As each adult female lays about 

 15 eggs, the multiplication of the mites is eventually 

 almost without limit, and it only leaves with the death of 

 the sheep or v/ith the removal of the mites through treat- 

 ment. 



The mite, Psoroptes communis, attacks sheep of all 



