EXPERIMENTS AGAINST CHICKEN LICE AND DOG FLEA. 11 



the dogs. In order to be of any value this material must be finely 

 pulverized, since, in the form that it is usually found on the market 

 (moth balls or rather coarse flakes and crystals), it can not be well 

 worked down to the skin, especially in the case of long-haired dogs. 

 This material seems to act somewhat as a repellent, causing the 

 fleas to drop from the animal in a partially stupefied condition. 



CHICKEN-LICE POWDERS. 



A large number of the so-called chicken-lice powders containing 

 various amounts of naphthalene, tobacco powder, sulphur and lime, 

 and occasionally small amounts of pyrethrum and phenols, were 

 tested and found to be more or less effective against the dog flea,, 

 depending on the amounts of the active ingredients (naphthalene, 

 nicotine, pyrethrum, and phenols) present and the fineness of the 

 powders. Only 4 of the 21 powders of this type tested were found 

 to be completely effective, although 10 of them killed from 75 to 95 

 per cent of the fleas. 



MISCELLANEOUS POWDERED MIXTURES. 



Five miscellaneous powders containing oils as the only active in- 

 gredient were tested and it was found that 18 per cent of sassafras 

 oil was completely effective and that 10 per cent or less of several 

 other oils was of no value. One powder composed of sawdust im- 

 pregnated with 33 per cent of wood-tar creosote was of no value, this 

 being due to the fact that the sawdust was so coarse that it did not 

 penetrate to the skin. 



MISCELLANEOUS POWDERED MATERIALS- 



The following powdered materials were found to be more or less 

 effective when used as dusts against the dog flea: Powdered cloves, 

 naphthalene, paradichlorobenzene, and powdered sassafras bark. 

 The results of experiments with them are given in Table IV. 



Table IV. — Results of dusting tests with various powdered materials against the dog flea. 



Name. 



Per cent 

 of fleas 

 killed or 

 repelled. 



Powdered cloves 



Naphthalene 



Paradichlorobenzene 



Powdered sassafras bark. 



100 



98-100 



100 



80-90 



The miscellaneous powdered materials tested and found to be of 

 no value against the dog flea were allspice, angelica root, borax, boric 

 acid, calcium sulphate, calcium fluorid, cornstarch, colocynth pulp, 

 diatomaceous earth, eucalyptus leaves, hellebore, air-slaked lime, 



