44 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1952 
t i on and deposit when planes were flown both upwind and crosswind 
over open ground at altitudes of 50 and 200 feet. It was shown 
that spray was distributed over a much wider swath when liberated 
,-it 200 feet, although there was no difference in the total volume of 
spray that reached the ground from the two heights. This indicates 
that in spraying large areas it is feasible to fly higher than previously 
recommended. As a result of these findings, it has been incorporated 
in hid specifications that airplanes he allowed t<> fly at heights of 
100 to 250 feet in tin' spruce budworm control program to he conducted 
in Oregon and Washington in L952. Prior to these tests heights 
recommended were from 75 to *2r>0 feet. 
Fifth Instar Spruce Budworm Larvae Most Vulnerable 
An airplane-spraying experiment was conducted in Quebec, Canada, 
in cooperation with the Bureau of Plant Industry, Soils, and Agri- 
cultural Engineering, State of Maine Forest Service, and the Quebec 
Department of Lands and Forests, to determine the proper timing of 
spray applications and the optimum degree of atomization and min- 
imum dosage of DDT sprays for spruce budworm control. Results 
indicated that the spray should be applied when the majority of 
budworm larvae are in the fifth instar. at which time new balsam 
fir foliage is an inch or more in length; that the spray should be 
atomized until the average spray droplet is medium in size (mass 
median diameter, 150 microns) : and that the minimum dosage for 
control is 1 pound of DDT in 1 gallon of spray solution per acre. 
Gypsy Moth Control Campaign Progresses 
Extensive acreages sprayed to control gypsy moth 
More than lMT.oOo acres of gypsy moth infested area were sprayed 
with DDT during the spring of 1952 through the cooperative efforts 
of the Bureau and State agencies. Ahont 15,000 acres were sprayed 
with ground equipment. The remainder was treated by airplane. 
Two federally owned C IT aircraft -prayed approximately 110,000 
acres, State-owned biplanes 20,000 acres, and commercial contractors' 
planes 71,000 acres. 
It is believed that the spraying of slightly more than 21,000 acres 
in or near Ransom Township. Lackawanna County, Pa., has eradicated 
the gypsy moth infestation there. Spraying of 1.3,000 acres of in- 
fested woodland in northwestern Connecticut and 32,000 acre- in 
western Vermont, mostly in territory near Lake Champlain, ha- pre- 
vented damage to forest growth by the gypsy moth in treated areas 
and will minimize the hazard of wind spread of small larvae into 
adjacent territory in New York State. Spraying of 150,000 acres in 
New- York included all known spots of gypsy moth infestation west 
of the Hudson River and in the northern Champlain Valley. Areas 
accessible to mist blowers in the generally infested area east of the 
Hudson River were also covered. 
Bait-lure material collected in Portugal 
A successful pupae-collection program was again carried on in 
Portugal in the spring of L952. Approximately 564,000 female gypsy 
moth pupae were collected. From these, nearly 350,000 abdominal 
tips of issuing moths were obtained for use in preparing hire material 
for future I rapping programs. 
