MAINE AGRICULTURAL EXPERIMENT STATION. 79 



tervals of several days to a week between each application, with 

 the lice powder described below, before they are put into the 

 cleaned houses. 



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

 at all times of the year practically free from lice. 



In keeping a poultry plant reasonably free from lice there 

 are two points of attack : One, the birds themselves ; the other, 

 the houses, nest boxes, roosting boards, etc. For the birds 

 themselves experience has shown that the best way to get rid of 

 the lice is by the use of a dusting powder to be worked into 

 the feathers. In using any kind of lice powder on poultry it 

 should always be remembered that a single application of pow- 

 der 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 pow- 

 der with a second at an interval of 4 days to a week. If the 

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

 make still a third application. To clean the cracks and crevices 

 of the woodwork of houses and nests of lice and vermin a 

 liquid spray or paint is probably the most desirable form of ap- 

 plication. 



The most efficient lice powder known to the writer is that 

 invented by Mr. R. C. Lawry, formerly of the Poultry Depart- 

 ment of Cornell University. This powder is made by incorpo- 

 rating the liquid mixture of 



3 parts of gasoline 



i part of crude carbolic acid 



in sufficient plaster of paris to take up all the moisture. 



Twe difficulties have arisen regarding the practical utility of 

 the powder as above described. In the first place a great many 

 druggists appear to have a deep-seated and ineradicable preju- 

 dice against furnishing their customers crude carbolic acid at 

 any price. Reports have reached the Station of druggists mak- 

 ing such utterly preposterous and absurd claims as that carbolic 

 acid is a highly explosive substance, which they do not dare to 

 handle! In the second place difficulty has arisen over the fact 

 that there are in the drug trade three grades of crude carbolic 

 acid. Two of these are very much weaker than the other and 

 are quite useless for making the lice powder. The three grades 



