BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 7 
senger, a Bureau employee with extensive experience in work of this 
type, in charge. 
Toward the end of the fiscal year contacts were made with State 
officials with the object of strengthening surveys for destructive in- 
sects. The plan being developed contemplates particular emphasis 
on protection against biological warfare. 
Much of the Bureau's research and service work was reviewed by 
commodity advisory committees, which made numerous helpful 
suggestions. 
COTTON INSECTS 
Supercrop of Boll Weevils Causes Huge Cotton Losses 
Boll weevils in 1950 reached their greatest destructiveness since the 
summers of 1921 and 1922. They were even more numerous and 
caused greater destruction than in 194T). when infestation averaged 
higher than in any other year after 1927. Losses would have been 
infinitely greater had not the growers used more insecticides than 
ever before. Cotton growers applied an estimated 750 million pounds 
of insecticides in 1950, as compared to 200 million pounds in 1949. 
Boll weevils caused an estimated 22.6 percent reduction in cotton 
yield, according to the Bureau of Agricultural Economics. 
Boll weevil numbers were at record highs over wide areas in 1950. 
As a result of a mild winter in 1949-50 the weevils survived in un- 
usually large numbers. In most of the States where the boll weevil 
was present conditions during the summer of 1950 were favorable for 
the insect. By the latter part of July serious infestations had been 
reported in northern Mississippi, Tennessee, northern Arkansas, and 
southern Missouri, where weevils usually cause little or no damage. 
In August damaging infestations were reported in southwestern 
Oklahoma in areas where the weevil had never been known before. 
Despite the enormous quantities of insecticides used, boll weevils 
caused the greatest reduction in yield ever recorded in Arkansas, Xorth 
Carolina, and Virginia. In Arkansas the reduction was 26 percent, 
in Xorth Carolina 54 percent, and in Virginia 63 percent. 
Insecticides Used in Vast Quantities 
Thousands of farmers for the first time used insecticides to control 
cotton insects. In Texas approximately 200 million pounds of in- 
secticides were used. In Mississippi, with about 2 million acres in 
cotton, more than 100 million pounds were used. In each of a dozen 
or more States millions of pounds of insecticides were used for the 
control of cotton insects in 1950. More insecticides were used early 
in the season for the control of over- wintering boll weevils, thrips, 
aphids, and cotton fleahoppers in South Carolina, Mississippi, and 
Texas than in any previous year. With the exception of a few fields 
in Texas, all fields given early-season applications of insecticides re- 
quired late-season applications for the control of the boll weevil. 
Another development in 1950 was the use of vast quantities of liquid 
sprays on cotton. Millions of gallons were applied to several million 
acres. 
972753—52 2 
