70 A NNCAL UK PORTS OF DEPARTMENT OF AGRICT'LTr RK, 1940 
with L5 percent in L930. Similar examinat ions at Florence in the 
spring 01 L940 showed LY6 live weevils per acre in comparison witb 
.V>s-j in r.»:',n. In general the unusually cold weather reduced the 
Weevil carry-over in L940 to the lowest point in many years. The 
examination of woods trash during recent years l>y means of spe- 
cially designed machines has proved of great value in determining 
the effects of climatic conditions on hibernating weevils and the 
Overwintering populations. A cold, late spring also caused later than 
average emergence. At Florence daily collections of weevils in a 
trap plot of cotton showed that 40 percent appeared after June 14 
when xpiares were present for ovipo>ition. in comparixm with 34.6 
percent during the preceding 1 3 years. At Leesburg no weevils were 
found in a trap plot of cotton until June 7, or after squares were 
large enough for food. 
Tests with calcium arsenates of different chemical and physical 
properties were continued in an endeavor to determine the most 
effective calcium arsenate for boll weevil control. Considerable Varia- 
tions exist as between different brands of commercial calcium ar- 
senate, and as these can be controlled in the process of manufacture 
the discovery of more desirable properties should lead to the manu- 
facture of a calcium arsenate giving better control at no increase 
in cost. Experiments with calcium arsenate containing low, inter- 
mediate, and high percentages of water-soluble arsenic pentoxide 
:;> determined by the New York method, similar to those reported 
last year, were repeated in randomized plots in South Carolina, 
Florida. Mississippi, and Louisiana, making a total of 68 replica- 
tions for each treatment for the 2 years. The results were similar 
to those of 1938 in that no significant differences were found, either 
in boll weevil infestations or in yields, in field plots treated with 
calcium arsenate containing 0.5, 4.6, and 10.3 percent of water-soluble 
arsenic pentoxide as determined by the Xew York method. In cage 
tests the calcium arsenate containing the highest percentage of water- 
soluble arsenic pentoxide was again most effective against the boll 
weevil. The discrepancy between the results in the field and in 
cages is thought to be due partly to the differences in aphid popu- 
lations following the use of calcium arsenate, as higher aphid attesta- 
tions occurred in the plots treated with the higher percentages of 
water-soluble arsenic pentoxide. 
I?i plot experiments at Tallulah, La.. State College. Miss., and Flor- 
ence, S. C, with mixtures of calcium arsenate and sulfur ( 1 to 1 and 1 
to 'i ) . the infestations and yields were about equal to those occurring 
where undiluted calcium arsenate was used in controlling the bofl 
weevil. These mixtures have the advantage of reducing the numbers 
of sucking insects and the amount of arsenic added to the soil. In 
cage tests sulfur and cah inni carbonate appeared to be better diluents 
for calcium arsenate tlian lime. 
Cryolites containing ; > ; >. Sli.S, and SD.tt percent of sodium fluo- 
alummate were tested as substitutes for calcium arsenate in 1 >* > 1 1 weevil 
control. The cryolite with S<).:5 percent of sodium Muoaluminate 
Caused severe binning of foliage in some cases, though this was avoided 
and a slight increase in toxicity secured by the addition of 1 percent 
ox Lethane spreader and sticker. The cryolites with the higher per- 
