DERRIS AS A PARACITICIDE 47 
larvae in it, and the kitten showed a moderate infestation. Three days 
later no live larvae were found, altho the kitten still harbored some 
fleas. The kitten was not completely cleared, altho the number of 
fleas was very considerably reduced. She had the run of a small 
room with dusty earth as a part of its floor. She was accustomed to 
lie in this dust a considerable part of the time, and this probably served 
as a flea breeding ground which was untouched by the powder. It 
seems reasonable to believe from the gradual reduction in the number 
of fleas found upon her, together with the non-appearance of live 
larvae in the bedding box, that under the usual conditions, where the 
cat has free run and sleeps largely in the usual bedding box, this 
method will effectually clear the animal of fleas. 
Since this same method had already been shown to be successful 
in the puppy experiment, no further work was done with dogs. 
This latter phase of the work was not undertaken until late in the 
summer and during the winter, and the possibility of its application 
to sitting hens was not worked out. There is, however, more than an 
even probability that it may be of value in the treatment of nesting 
material for sitting hens for the purpose of destroying lice and mites. 
There are no data on its effect upon the viability of incubating eggs, 
but since the effective agent is a non-volatile resin, and tobacco dust 
is known to be non-injurious, there is no reason to anticipate any ill 
effects from its use. The fact, furthermore, that it retains its efficiency 
upon exposure to air without deterioration would add very consider- 
ably to its value for this purpose. It is intended to carry out investi- 
gations upon this phase of its use. 
The work which was done in testing the efficiency of the powder 
as a louse remover with chickens showed it to be effective, but no 
more so than the familiar sodium fluoride. Its action is slower but 
equally certain. In the dry form it has certain advantages. It is not 
so irritating to the eyes, nose, and lungs of either the operator or the 
fowl as is the dry fluoride. It has no advantage over the fluoride dip 
treatment, is not so rapid in its action, requires more time to apply, 
and in all probability will never be as inexpensive as the fluoride treat- 
ment. There is no doubt, however, of its efficiency so far as louse 
removal is concerned. 
A series of experiments with cockroaches was also undertaken. 
Here the 20% derris-80% tobacco dust mixture was also found to be 
effective, altho somewhat slow in action. Roaches forced to run through 
the powder and then confined in cages or small glass jars all died 
within twenty-four hours. These roaches were forced to run over a 
