BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 17 
experiments in the South and in California. Tetraethyl pyrophos- 
phate was also effective against the cabbage aphid, and dusts were 
better than sprays. Dusts containing this insecticide were found to be 
superior to the formerly recommended nicotine, and since they are also 
cheaper they are now being widely used by growers. A 1-percent 
gamma benzene hexachloride dust prepared from the essentially pure 
gamma isomer was superior to a dust of the same gamma-isomer con- 
tent prepared from technical benzene hexachloride against associated 
infestations of the turnip aphid and cabbage caterpillars. 
Cost of Controlling Cabbage Caterpillars Reduced 
DDT dusts have continued to give good control of the several species 
of caterpillars occurring on cabbage before the heads begin to form. 
In commercial practice this material has almost completely replaced 
the rotenone, arsenic, and fluorine insecticides formerly used, at a 
lower cost. A dust containing 1 percent of DDT plus 2 percent of a 
methylated naphthalene was found to be as effective as a 3-percent 
DDT dust, and also cheaper. 
Insecticides Kill Melonworms and Pickleworms on Cucumbers 
Gamma benzene hexachloride and parathion dusts containing 1 per- 
cent of the active ingredient gave satisfactory control of the melon- 
worm and the pickleworm on cucumbers without causing appreciable 
injury to the plants. * Technical benzene hexachloride, chlordane, and 
DDT injured cucumber plants in tests near Charleston, S. C. For use 
during the picking season dusts containing 20 percent of sabadilla, 40 
percent of ryania, or 0.3 percent of pyrethrins were more effective than 
1-percent rotenone dust against the pickleworm. 
Remedy Sought for Serpentine Leaf Miner 
Outbreaks of the serpentine leaf miner on tomatoes, melons, and 
certain other truck crops in the Southwest and also in Florida have 
made it necessary to search for a means of controlling this insect. In 
California toxaphene and chlordane were effective either in dusts or in 
concentrated sprays. These insecticides also controlled the tomato 
fruitworm. In Arizona sweetened sprays containing chlordane or 
toxaphene were very toxic to adults of this leaf miner, but they also 
greatly reduced the number of its parasites. Some evidence has been 
obtained that these baited sprays also kill the leaf miner larvae within 
the leaves. 
Soil Insecticides for Wireworms Evaluated 
Recommendations on the use, of ethylene dibromide as a soil f umi- 
gant for the control of wireworms in irrigated lands were issued during 
the year. 
Tests with soil insecticides showed that DDT, chlordane, and toxa- 
phene will materially reduce wireworm populations. DDT acted 
more slowly than the other materials, but experiments thus far indi- 
