34 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 194 4 
dicate need for change, or to provide for expansion at the termination 
of the war. 
NEW AND VERY EFFECTIVE METHOD OF CONTROL INDICATED 
During the year DDT was tested on an experimental control basis 
against gypsy moths. A 20-acre woodland tract in Pennsylvania and a 
5-acre wood lot in New York, in which rather heavy infestation 
existed, were treated with DLVr in concentrated spray form at the rate 
of 5 pounds per acre. The spray was applied by a specially constructed 
spinner-disk apparatus attached to a biplane. Application was made in 
the Pennsylvania tract early in May before leaves had developed and 
prior to hatch of gypsy moths. In New York treatment was applied 
after leaves had fully developed and when gypsy moths were in the 
second larval stage. From a relatively few hours after the treatment 
to the close of the fiscal year no living gypsy moths were found in 
either tract. 
Other small-scale demonstrations with DDT as an emulsion, in 
aerosol form, and in a dilute spray mixture were conducted. All 
methods proved to be spectacularly effective against gypsy moths in 
all stages of larval development. As a final check all treated areas 
will be carefully observed through the egg-laying season. 
It is believed that, when available for the purpose, application of 
DDT by aircraft will afford a cheaper and much more effective method 
of control and eradication of gypsy moths than any method previously 
used. 
These experiments with DDT in spray form were carried out co- 
operatively with the Division of Forest Insect Investigations, and those 
with the material in aerosol form with the Division of Control 
Investigations. 
PROGRESS IN PENNSYLVANIA 
The effectiveness of gypsy moth control is evidenced by the fact 
that at the close of the year the size of the infested area in Pennsylvania 
had been reduced to 556' square miles. This is in comparison with an 
area of 1,040 square miles in 193^. As a result the State quarantine 
was revised to remove from regulation more than 400 square miles 
where infestation had previously existed. 
SPECIAL EMPHASIS PLACED ON SURVEYS 
During the year surveys were conducted on more than 4 million 
acres within and beyond the limits of spread of the gypsy moth, by 
using a sex attractant. While no additional infestations were found 
beyond the area of general distribution in Pennsylvania, the gypsy 
moth was detected in New York State in several townships north 
and northeast of Albany and Schenectady Counties, where infestation 
had been discovered by the same type of survey during the previous 
year. This spread increases the extent of areas needing I reatment, but 
since the wood lots in these area- are small compared with the acreage 
in pastures and under cull i vat ion, the application of extensive com rol 
and eradication method- when manpower and materials are available 
BUOUld result in elimination of this westward extension of infestation. 
