BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 75 
field corn. The 60-pound treatment caused a slight reduction in the 
average green weight of the soybeans, and both the 25- and 60-pound 
treatments caused slight reductions in the average green weights of 
.the rye. In the same 4-year study chlordane at rates up to 19 pounds 
per acre and, over a 3-year period, aldrin at 3.2 pounds and dieldrin at 
2.9 pounds per acre had no deleterious effect on any of the foregoing 
crops. In field tests at widely separated points DDT applied in 1944 
at the rate of 2.5 pounds per acre to turf continued to give complete 
protection through 1951. The oldest treatment has shown no change 
in effectiveness during the T 1 - years following application. This was 
in spite of the fact that the quantity in the soil had dropped more 
than two-thirds. 
DDT and Other Insecticides Gradually Lost From Soils 
DDT does not remain indefinitely in the soil after being applied for 
Japanese beetle control. Studies by the Moorestown, X. J., labora- 
tories of turf plots maintained at a number of locations from Massa- 
chusetts to Xew Jersey have shown that after a few years it disap- 
pears fairly fast. The average carry-over of DDT after 2 years was 
92 percent ; after 4 years, 43 percent ; after 6 years, 36 percent ; and 
after 7 year-. 29 percent. 
Chlordane decreased more rapidly than the DDT — to 30 percent of 
the amount applied in 1% years whereas more than this percentage of 
DDT still remained after 6 years. After 40 months, 46 percent of 
the toxaphene and 44 percent of the TDE remained, and after 12 
months 67 percent of the dieldrin and 33 percent of the aldrin. 
WHITE-FRINGED BEETLES 
Surveys Show Annual White-Fringed Beetle Spread 
By the end of 1951 white-fringed beetles were known to occur in 
143 counties in 8 States. During the year infestations were found 
for the first time in Lauderdale County, Miss. ; Darlington and Flor- 
ence Counties, S. C. ; and Tipton County, Tenn. In these 143 coun- 
ties, 340,000 acres have been determined as infested. As a result of 
the control program no beetles could be found in 1951 on 12 percent of 
this acreage. Light infestations are present on 68 percent, moderate 
numbers on 13 percent, and heavy infestations on only 7 percent. In 
17 of the previously known infested counties, no specimens of beetles 
can be found. During 1951, more than 200.000 certificates and per- 
mits were is>ued authorizing the movement of host material. 
^ ide Cooperation in Controlling White-Fringed Beetle 
During the year contributions for white-fringed beetle control by 
the States, counties, municipalities, industrial concerns, and other 
establishments and individuals approximately equalled Federal ex- 
penditures for this purpose. These contributions represented a large 
increase over previous years. They were the direct result of efforts by 
the Bureau to bring about a more equitable distribution of the work- 
load among those benefiting from the control program. 
