-127- 
Treatment with derris dust gave promising results against this 
tiok on sheep and cattle, although its complicated life history ren- 
ders control more difficult. The warble-fly wash, which contains 
standardized derris, was applied over the shoulders and around the 
backs of the heads of oattle, and in every instance the animals re- 
mained free of ticks* Good results with this method were reported 
by stookmen, but the dry derris powder method would be safer, par- 
ticularly in cold weather.-- Gunn (247 , 248 ) • 
Arsenical dips are still the best means of ridding stock of ticks, 
particularly D* andersonl , but their effectiveness in giving pro- 
tection from "reinfestation remains in doubt* Derris and pyrethrum 
are highly lethal to ticks and relatively nontoxic to mammals, but 
their cost is high and their lasting quality poor* It was found that 
tioks would readily infest lambs treated heavily with derris powder, 
and although many were killed, a few suooeeded in attacking and en- 
gorging*— Mail (388) * 
Derma cent or nigrolineatus (Pack*), the brown winter tick 
A wash of 7 ounces of derris (5 percent of rotenone), 1*5 ounces 
of neutral soap, and water to make 1 gallon was very effective, kill- 
ing even the most resistant adults and protecting the animals from 
reinfestation to a considerable degree*— Bishopp (52); U* S# Bureau of 
Entomology and Plant Quarantine (624 , p# 48)* 
Dermacentor sp* 
In the Philippine Islands a dust containing 1 to 2 percent of 
rotenone with cassava starch killed ticks on dogs in 24 to 72 hours* 
-De Jesus and Gapuj (324) • 
Dexmoentor variabilis (Say) # the American dog tick* the common wood 
tick 
The most effeotive way to prevent injury to dogs by ticks is to 
wash or immerse the dogs twice a week in derris dip, which is prepared 
by dissolving an ounce of mild soap in a gallon of warm water and 
stirring 2 ounoes of fine derris or cube (3 percent of rotenone) into 
the solution* If a dip cannot be used conveniently, derris or cube 
powder may be applied as a dust, care being taken that it penetrates 
the hair and reaches the skin*— Bishopp and Smith (57); Harwood (268 ) * 
If dogs that have access to the house are not kept free of ticks 
by dusting with a mixture of derris root and talc (3:1) or by some 
other means, elimination of the young ticks may be extremely difficult* 
— Headlee (274). 
