BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 
23 
tick for 90 to 120 days. The spraying of salt troughs and the areas 
under them with equal parts of kerosene and used motor oil also de- 
stroyed many of these ticks. When both these treatments were used, 
marked reductions of tick populations in pastures were observed. 
Tickicides containing 5 percent of DDT in nondrying adhesives 
were prepared and used in preliminary field tests against the Gulf 
Coast tick. The period of protection from reinfestation given by these 
formulas ranged from 3 to 5 weeks, whereas the materials now in 
use by ranchmen did not give protection for more than 8 days. 
IMPROVEMENTS IN CONTROL OF LICE ON LIVESTOCK 
In tests made in the interest of conserving rotenone, 2.5 pounds of 
cube powder (5 percent rotenone) in 1.000 gallons of water used as 
a dip killed all the motile stages of the short-nosed cattle louse. When 
100 pounds of wettable sulfur was added to this dip, it was effective 
for a second dipping 2 weeks after the first. A dip containing 5 
pounds of cube, without sulfur or with only 50 pounds of sulfur, did 
not kill all the lice when it was held for a second treatment. Other 
tests showed that wettable sulfur, without rotenone, used at the rate of 
150 pounds per 1,000 gallons of water did not give satisfactory 
control of this pest. 
DDT was found to be remarkably effective for controlling this and 
other less resistant species of cattle lice. As little as 0.06 percent of 
DDT in a water suspension gave complete mortality of the motile 
stages of all species of cattle lice. 
Emulsions containing 0.1 percent of DDT killed the motile stages 
of all species of lice on Angora goats, and the material from a single 
dipping remained in the hair long enough to kill the young lice that 
hatched from the eggs. 
INSECT IDENTIFICATION 
More than 700,000 species of insects are already known, and a larger 
number still remain to be discovered and described. Many with sig- 
nificantly different habits, and consequently requiring different meth- 
ods of control, are so similar that they readily pass for each other. 
Authoritative identifications by specialists are, therefore, prerequi- 
site to the use of effective control measures. Moreover, specialized 
research in insect classification must be continued to provide an in- 
creasingly sounder basis for identification. 
Identifications were reported for 59,956 insect samples contained in 
33,668 lots. Of these 28 percent represented interceptions in imports 
from abroad and 29 percent collections made in the course of special 
surveys; 25 percent were from research and control activities of this 
Bureau and other Federal agencies; 9 percent from agricultural col- 
leges and experiment stations of the various States and insular pos- 
sessions; 5 percent from individuals, private agencies, and pest-con- 
trol operators: and 4 percent from foreign governmental agencies and 
institutions, largely in the Western Hemisphere. 
Research in insect classification and anatomy designed to improve 
the bases for exact identification in certain insect groups resulted in 
completion of 27 manuscripts, totaling 831 pages, for publication. 
Direct assistance given the Army and Navy involved identification 
of approximately 2,000 samples of mosquitoes, mostly from the war 
