BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 51 
Further extensive trials of the poisoned bail made of bran, sodium 
fluosilicate, and water on several thousand acres of infested land con- 
tinued to give excellent results, with kills averaging oyer 90 percent of 
the crickets. These tests included the use of a bait in which a small 
amount of lubricating oil was substituted for the water, the bait being 
applied by plane on about 3,000 acres of infested land in Nevada, with 
better than 90 percent kill. 
WHITE-FRINGED BEETLE 
In field cages all forms of cryolite tested against the white-fringed 
beetle gave better than 90 percent kill of the adult beetles, but on 
cotton, calcium arsenate gave better control than cryolite. Several 
kinds of cryolite dusted on peanut and field-pea foliage caused no 
injury to those plants. As a result of plot tests of dusting for control 
of the adults, the population of the next generation of grubs in the soil 
was lowered. In an experiment on peanuts the fall population of 
grubs in the undusted plots was 77.4 per square yard as compared with 
only 22.9 per square yard in the dusted plots. 
In tests of severaf f umigants to kill the grubs in the soil, carbon 
disulfide was the most efficient where complete mortality, regardless of 
plant injury, was the objective. In June, with soil temperatures in 
excess of 76° F., a dosage of 11 milliliters per square foot gave 100 
percent kill to a depth of 16 inches. 
Trials of lead arsenate as a soil insecticide gave encouraging results 
in pot tests, even with applications as light as 250 pounds per acre, 
but in field tests it was less effective and reduced the yield of peanuts 
22 percent. 
As an ovicide, coal-tar creosote in a 30-percent emulsion was 100 
percent effective. 
In cultural-control experiments it was demonstrated that a fallow 
conducted during the period of adult activity, from May to November, 
was quite as effective in reducing the grub population as a full year's 
fallow. Results also indicated that the population rapidly diminished 
in abandoned farm land but that a 2-year period of complete fallow 
failed to eradicate the insect. 
In crop-rotation studies higher larval populations were produced 
in peanuts and in corn intercropped with velvetbeans than in pure 
cultures of corn or cotton. Such crops as winter oats, producing an 
abundance of fibrous roots, were not seriously injured in the presence 
of heavy grub populations. Tobacco and sugarcane planted in grub- 
infested soil suffered severe damage. 
INSECTS ATTACKING CORN 
In experiments with contact insecticides for use on corn in emer- 
gency control of chinch bugs, rather satisfactory kills without injury 
to the corn were obtained with oil emulsions containing either derris 
extracts or nicotine sulfate. These sprays are promising, at least for 
use on restricted plantings of high-value pedigreed corn grown for 
seed. 
Further improvements were made in the use of mineral oil for the 
control of the corn earworm in sweet corn by the addition of small 
percentages of pyrethrum extract or dichloroethyl ether. 
