FATE PLANT BOA"D
J'lery 1948 ET-49
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
By R. D. Chisholm, Division of Insecticide Investigations
and W. C. Fest, Division of Fruit Insect Investigations 1/
A laboratory study of the effectiveness of insecticide dusts in kil-
ling Japanese beetles (Popillia japonica Nerm.) involved designing a
duster to meet the requirements of the tests. Briefly, it was necessary
to distribute amounts ranging from 0.4 to 3.2 grams of dust in each of
six cages approximately 3 by 6 by 3 feet. This paper describes the
duster which was developed for this purpose.
Description of Duster
The duster is shown in figure 1. A hose (A) connected with an air
supply regulated at a pressure of 50 pounds per square inch is screwed
into the inlet end of a lever-controlled spring valve (B) having a dis-
charge orifice 1/16-inch in diameter. A standard-pipe-size 1/8-inch
tee (C) is screwed onto the discharge end of valve B, so that the valve
orifice is located at the center of the tee. A 1/8- by 4-inch standard
pipe nipple (D) is screwed into the tee outlet on the same axis as the
valve. The small opening of a 60-degree funnel (E) having a top opening
1 1/2 inches in diameter is fitted tightly into the third tee opening,
which is directed vertically upward. All metal parts are of brass.
Figure l.--Perspective drawing of duster.
gThe authors are indebted to G. J. Baetzhold, Division of Japanese
Beetle Control, for the drawing presented in this paper.
S2 UNIVERSITY OF FLORIDA
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Operation of Duster
The duster is operated by opening spring valve B, by depressing its
lever, and then pouring the insecticide into funnel E. The high-velocity
air stream released from the valve, acting on the principle of the air
jet, causes the insecticide to be drawn from funnel E into tee C, and
discharged from nipple D as a dust cloud. The entire operation requires
about 1 second.
Doses ranging from 0.4 to 3.2 grams were divided in half, and the
portions were distributed with a high degree of uniformity from each end
of the test chambers. In preliminary tests it was found that dispersion
of the insecticide, range of the dust cloud, and uniformity of the deposit
were dependent upon the pressure of the air used and the length of the
discharge nipple. The duster may be adapted to use on a larger scale by
modification of these factors and the sizes of the parts.