External Parasites 205 



During the past few years this Station has adopted another 

 method of freeing the birds of lice, namely the use of mer- 

 curial ointment. An ointment has certain very distinct 

 advantages over any powder. It is much easier to apply, 

 and requires less of the poultryman's time, which is an im- 

 portant factor on a large plant. Further a mercurial oint- 

 ment is more efficient and lasting in its effect as a parasiticide 

 than any powder. 



The form of ointment which we have used is the ammoni- 

 ated mercurial ointment U.S. P., with the exception that 

 we have the druggist make it with a lard base, instead of 

 the lanolin base called for by the Pharmacopoeia. Others 

 use the blue ointment of the U.S. P. for the same purpose. 

 It is probably mqre effective, part for part, but it is also 

 more expensive. 



The proper method of applying the ointment is to rub 

 well on to the skin three pieces of the ointment, each as 

 big as a small pea. One of these pieces should be rubbed 

 on just under the vent, the other two under the wings. 

 The ointment should never be simply daubed on and left 

 as a lump. If it is so done, the bird is very liable to get 

 some of it in the mouth and a case of mercurial poisoning 

 will result. 



As a result of these methods the Station's poultry plant 

 is at all times of the year practically free of lice. 



This method keeps the flock free from lice and the mites 

 which live upon the surface of the skin, but would not de- 

 stroy those mites which penetrate the skin and cause scabies. 

 These and other more rare parasites should be destroyed 

 when present by special methods. The description of, and 

 treatment for, each class of external parasite is given below. 



