EXPERIMENTS AGAINST CHICKEN LICE AND DOG ELEA. 9 



Pyrethrum. — Good, fresh pyrethrum powder is one of the best 

 insecticides for the control of lice, but is too expensive for use on a 

 large scale. 



THE DOG FLEA. 11 



METHODS OP TESTING. 



The tests of insecticides against the dog flea were made under nat- 

 ural conditions except that the dogs were not allowed to return to 

 the kennels until after the final records had been taken, as the kennels 

 were, at all times, badly infested with fleas. Before each test the 

 dogs were carefully examined to ascertain the degree of infestation 

 and, unless a fairly large number of fleas was found, the animal was 

 not used. After the dogs had been treated they were confined in 

 large wire cages or tied to trees in the open air. Examinations were 

 made at the end of 2, 24, or 48 hours, but no test was closed at the 

 end of 2 hours unless nearly all of the fleas had been killed or re- 

 pelled. It was considered that a material which had produced no 

 noticeable results in 24 hours was ineffective. The sprays were 

 applied with a hand sprayer, and the dusts with a small powder gun 

 or a tin shaker. Both dusts and sprays were well rubbed in with 

 the hand unless otherwise noted. In testing the washes, the dogs 

 were placed in a tub containing 4 or 5 inches of the wash to be tested 

 and thoroughly scrubbed by means of a sponge or cloth dipped in 

 the liquid. In the dipping tests the animals were immersed for 1 

 or 2 minutes in the solution until all but the mouth and eyes were 

 covered and the top of the head was well soaked by hand. In every 

 case the materials to be tested were very thoroughly and carefully 

 applied, so that these results represent their maximum value. 



The results are given as "per cent killed or repelled," and these 

 figures are, of course, only estimates. In most cases, even when an 

 effective remedy was used, very few dead fleas were found on the 

 dogs at the time of examination, although there is very little evidence 

 that any material, with the possible exception of naphthalene, actu- 

 ally drove the fleas from the dogs without killing them. 



PYRETHRUM POWDER. 



Table II gives the results of tests with pyrethrum powder and 

 powdered pyrethrum stems against the dog fleas. 



This table shows that pyrethrum powder (insect powder, Dalma- 

 tian powder, or Persian insect powder) is very effective but that 

 powdered pyrethrum stems are of no value against the dog flea. 

 It also shows that while 4 or 10 per cent of good pyrethrum is of 

 value, at least 50 per cent should be used in a mixed powder to 

 secure the best results. 



11 Ctenocephalus canis Curt. 



