72 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



Those attempting the control of hce on poultry have become im- 

 pressed with the difficulty attending this operation for the reason 

 that these small active forms increase in such numbers as to make 

 many types of control impracticable or only partially efficient. 



Por a long time powders and dust baths have been recommended 

 to those who would free their poultry from lice but it is the ineffective- 

 ness of this method that I would like to emphasize at this time. 



To determine the relative value of various means of control, one 

 hundred and fifty well grown white leghorn pullets and male birds 

 were used in the tests made a year ago last summer. This stock 

 was badly infested with lice and they were placed in separate coops 

 and runs so that they would keep under control and at the same time 

 have sufficient exercise. Pyrethrum, the Lawry or Cornell, powder, 

 lard, vaseline, mercurial ointment normal strength, and mercurial 

 ointment dilutes one to two parts, one to three parts, one to five parts, 

 one to ten parts, were tried, together with the usual check lot, each lot 

 consisting of from ten to twelve birds. 



The results from these tests were very marked, showing distinctly 

 the inefficiency of the dusting methods even when the operation was 

 repeated several times, for the test extended over the whole summer. 

 The vaseline and lard were more effective over a longer period than 

 the powders. Of the powders, the Cornell (Lawry) powder made up 

 of two and one-half pounds of plaster of paris, one-fourth pint of crude 

 carbolic acid and three-fourths pint of gasoline, caused the death of 

 many lice soon after the powder was applied. As a demonstration of 

 this, these lice were shaken on a large clean piece of paper. This 

 result seemed a positive evidence of effectiveness, but on examining 

 the birds so dusted a few days afterward the numbers of lice seemed to 

 have been but slightly diminished, making continued applications 

 necessary, yet never quite freeing the hens of the lice. 



The fact that a hen dusted with a powder shakes much of that 

 powder out of her feathers soon after the mixture has been applied, 

 accounts for a loss of some of the effectiveness of this method. Most 

 dusts, too, lose their effectiveness long before the next generation of 

 lice is hatched. The dust baths are likely to become non-effective 

 by being covered with feathers and accumulated excrements, making 

 them damp and hard. 



The use of the mercurial ointment did not cause the death of the 

 lice so quickly, but within a few days no lice could be found upon the 

 hens and this condition lasted over a period of from eight to sixteen 

 weeks. The mercurial ointment caused some burns but the dilution 

 of one part mercurial ointment to two parts vaseline controlled the 

 lice and caused only a few slight irritations that lasted but a short 



