RESULTS OF EXPERIMENTS AGAINST THE CHICKEN MITE. 5 



NAPHTHALENE. 



Since naphthalene was efficient as a fumigant, it appeared that 

 this material might have effect as a dust. Naphthalene of 40-mesh 

 fineness was dusted in nest boxes at 100 per cent, 75 per cent, 50 per 

 cent, and 23 per cent strengths. 



In the first of these tests it was efficient, in the second and third 

 (with wheat flour as diluent) moderately so, and in the last (with 

 sand as diluent) inefficient. Pure naphtnalene dusted on roosts was 

 efficient in two out of four tests. A 4 per cent naphthalene in lime 

 was inefficient in a roost test, while a 12 per cent preparation in sul- 

 phur and lime proved moderately efficient when dusted in an infested 

 coop. Coarse naphthalene was inefficient when dusted in two in- 

 fested chicken houses, while a naphthalene of 40-mesh fineness was 

 of slight value in a third. 



It appeared that naphthalene is efficient only in a small circum- 

 scribed area where it may have a fumigation effect. In more open 

 places it has a rather weak repellent effect. Dissolved in kerosene, 

 the mixture was not more efficient than pure kerosene, but dissolved 

 in gasoline the resultant mixture was more efficient than pure gasoline. 



In practice, dusting with naphthalene is not a feasible method for 

 the control of the chicken mite. 



DERRIS. 



Four infested chicken houses were dusted with the finely ground 

 powder of the roots of Derris sp. Undiluted dust was efficient in one 

 house and temporarily so in another. In a third house a 75 per cent 

 dust was only moderately efficient, in a fourth test a 50 per cent dust 

 was inefficient. Flour was used as a diluent. 



Derris powder is a remedy of value, but it would appear that two 

 or more applications are necessary and that it loses its efficiency if 

 diluted more than 25 per cent. Its action on larvae and adult mites 

 is first to stupefy them, the insects dropping to the ground and dying 

 after two or three days. The material is rather unpleasant to apply. 



PYRETHRUM. 



Finely ground flowers of Pyrethrum cinerariaefolium and P. roseum 

 were efficient when dusted undiluted in a nest box and when applied 

 in a chicken house in two applications 33 days apart. Another 

 house was dusted once and a third twice (32 days between applica- 

 tions). These latter tests showed only moderate efficiency, but 

 conditions were very unfavorable in the house treated twice. 



Pyrethrum diluted with flour to 75 and 50 per cent strengths was 

 inefficient in chicken houses. 



Pyrethrum is somewhat less efficient and less unpleasant to handle 

 than derris-root powder. 



SABADILLA SEEDS. 



Finely ground sabadilla seeds (Schoenocaulon officinale) were effi- 

 cient in treating an infested nest box. 



It appears probable that this material equals derris in efficiency, 

 but no chicken house tests were made to determine this point. 



