22 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1944 
Early in the spring serewworms moved into northern grazing areas 
along with Bhipments of animals, but the prompt use of Smear 02 pre- 
vented most of the losses that would ordinarily have occurred among 
the infested animals. The pest became established in many local- 
ities where stockmen were not familiar with it or with the use of this 
smear, and in such instances the losses were avoided only because of 
the timely surveys and the advice given by Bureau workers and by the 
early procurement of Smear 62. 
Some outstanding results have been obtained in preventing infes- 
tations of fleece worms (Phormid unhid Meig.) with a mixture of 
benzene and a wetting agent. Further tests are needed on a larger 
number of animals on ranches. 
With another formula used on laboratory animals it has been pos- 
sible to reduce the time required for healing wounds infested with 
fleece worms, and the average number of reinfestations has been re- 
duced from approximately four per animal to less than one. When 
this treatment is applied to the infested wool of sheep, it penetrates 
the fleece and kills all fleece worm larvae upon contact. 
Screwworm infestations occur in wounds caused by horn flies. 
Sprays with DDT for the control of horn flies attacking beef cattle 
under ranch conditions have greatly reduced the fly populations as 
well as the number of severe injuries caused by bites of large numbers 
of flies on small areas under the belly, about the rump, and at the 
base of the horns. A spray containing 1 percent of DDT killed all 
horn flies that alighted on the treated animals for 1 week. Range 
cattle sprayed with % pint per animal of a 0.2-percent DDT emulsion 
remained almost entirely free of flies for 7 days. 
ROTENONE EXTENDERS RECOMMENDED FOR CATTLE GRUB CONTROL 
The practical use of rotenone-bearing powders when mixed with 
finely ground tripoli, volcanic ash, or pyrophyllite has been demon- 
strated under ranch conditions in the treatment of cattle for the control 
of cattle grubs. These diluents have been found to be much more 
effective than either sulfur or talc because they penetrate the hair 
better. Because of the good results obtained with them as diluents 
for ground cube or derris, they have been recommended for use in 
dusts for cattle grub control and as a means for extending the available 
rotenone. Sprays containing only finely ground cube or derris root 
in water also gave a high kill of cattle grubs. When applied at a 
nozzle pressure of 400 pounds or more., a suspension of cube or derris 
powder in water gave better results than when these powders were 
mixed with wettable sulfur or with a wetting agent in water. When 
the spray was applied at a low pressure, the addit ion of a small amount 
of sodium lauryl sulfate somewhat enhanced its effectiveness. 
Dusts containing 10 percent of DDT were found to be almost 
entirely ineffective against cattle grubs. 
NEW TREATMENTS FOB TICKS AFFECTING ANIMALS DEVELOPED 
Investigations on control of the winter tick were concerned princi- 
pally w'uii washes thai would kill all stages and protect horses against 
reinfestation. Considerable progress was made toward the develop- 
ment of a wash consisting of I )I >T and soluble pine oil in water. 
With a nondrying adhesive containing an insecticide it was possible 
to protect the ears of tattle, sheep, and goats from the spinose ear 
