BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 77 
centages of sodium fluoaluminate gave better control than those with 
the lower percentages, but improvements are needed in dusting quali- 
ties to secure the thorough coverage of the plants that is necessary for 
weevil control. Although calcium arsenate or mixtures of calcium 
arsenate and sulfur gave better control and larger gains than any of 
the four cryolites tested, cryolite might be sufficiently toxic to control 
the weevil if the dusting qualities could be improved. The fluosilicates 
of barium and sodium were likewise not so effective against the boll 
weevil as calcium arsenate. 
Interest in the use of sweetened poison (1 pound of calcium arsenate, 
1 gallon of molasses, and 1 gallon of water applied with a mop) for 
boll weevil control has continued in some of the Eastern States. Since 
no dusting machinery is required, applications can be made at any time 
of the day, and the cost per acre is low. Tests have therefore been 
carried on over a period of years at Florence, S. C, in which the effec- 
tiveness of applying sweetened poison, or "mopping," has been com- 
pared with that of the standard treatment of dusting with calcium 
arsenate after 10 percent of the squares have become infested, and 
with that of mopping followed by later dusting. Over the 12-year 
period of these tests (1928-39) boll weevil damage ranged all the way 
from severe to very light. The average gains over the untreated 
checks during this period were 40.6 pounds of seed cotton per acre, or 
5.2 percent, for the mopping; 275.8 pounds, or 30.4 percent, for 
dusting with calcium arsenate; and 316 pounds, or 38.4 percent, for 
the combined mopping and dusting. The average costs per acre per 
season for these three methods were, respectively, approximately $1.24, 
$3.67, and $4.26. In South Carolina with about V/ 2 million acres of 
cotton, enough molasses was reported sold in 1939 to mop 500,000 acres 
three times during the season. Assuming that the average difference 
of 235 more pounds of seed cotton per acre from dusting than from 
mopping could have been obtained on this acreage, the farmers lost 
some 80,000 bales of cotton in 1939 by using sweetened poison instead 
of the more effective calcium arsenate 'dust. 
In the sea-island cotton areas of Georgia and Florida the weevil 
infestations were light early in the season, but severe boll damage was 
caused by the late-season migrating weevils. At Tifton, Ga., attempts 
were made to develop a timed schedule of dusting based on the squaring 
date of the cotton plant and predetermined intervals between appli- 
cations that would not require infestation records to be made. Results, 
based on the percentages of squares infested and the damaged locks 
of harvested cotton, were equal to those from dusting after the usual 
10 percent infestation. Plots sprayed with calcium arsenate gave 
fair control early in the season but again failed to give adequate 
control late in the season in both States. Mixtures of calcium arsenate 
and sulfur dusts were not so effective as undiluted calcium arsenate 
for weevil control, and while the increases in yields from the mixtures 
were larger than from calcium arsenate at Gainesville, Fla., part of the 
gains were probably due to control of other insects. The application 
of sweetened poison, or "mopping," also failed to give effective control 
in the experimental plots or when used by growers on a field basis in 
a number of fields under observation. 
