EXTERNAL PARASITES 41 



When the treatment of individual birds for lice 

 becomes necessary some kind of powder dusted 

 into the feathers thoroughly, seems to be, on the 

 whole, the most effective and advisable remedy. 

 The powder used must be of such a nature, how- 

 ever, that it will be effective. There are-so-called 

 *Mice powders'' on the market which are no more 

 effective than an equal quantity of any inert pow- 

 dered substance would be. It is not only a waste 

 of money but of time as well to use such pow- 

 ders. At the Maine Station no lice powder has 

 been found that is so satisfactory as that origi- 

 nally invented by Mr. E. C. Lawry, formerly of the 

 poultry department of Cornell University. This 

 powder (which can be made at a cost of five cents 

 per poimd) is described as follows by the Maine 

 Station : 



In using any kind of lice powder on poultry, it should al- 

 ways be remembered that a single application of it is not 

 sufficient. When there are lice present on a bird there are 

 always unhatched eggs of lice (nits) present, too. The 

 proper procedure is to follow up a first application of powder 

 with a second at an interval of four days to a week. If the 

 birds are badly infested at the beginning, it may be necessary 

 to make still a third application. 



The lice powder which the Station uses is made at a cost 

 of only a few cents a pound, in the following way: 



Three parts of gasoline and one part of crude carbolic 

 acid, 90-95 per cent strength, or, if the 90-95 per cent strength 

 crude carbolic acid cannot be obtained, take three parts of 

 gasoline and one part of cresol. 



Mix these together and add gradually, with stirring, enough 

 plaster of paris to take up all the moisture. As a general rule 

 it will take about four quarts of plaster of paris to one quart 

 of the liquid. The exact amount, however, must be deter- 

 mined by the condition of the powder in each case. The 

 liquid and dry plaster should be thoroughly mixed and stirred 

 so that the liquid will be uniformly distributed through the 

 mass of plaster. When enough plaster has been added the 

 resulting mixture should be a dry, pinkish-brown powder 

 having a fairly strong carbolic odor and a rather less pro- 

 nounced gasoline odor. Do not use more plaster in mixing 

 than is necessary to blot up the liquid. 



This powder is to be worked into the feathers of the birds 



