January 1948 
 
 ET-2A9 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 
 Bureau of Entomology and Plant i^uarantine 
 
 LABORATORY DUSTER 
 
 By R. D. Chisholm, Division of Insecticide Investigations 
 and W. G. Fest, Division of Fruit Insect Investigations i/ 
 
 A laboratory study of the effectiveness of insecticide dusts in kil- 
 ling Japanese beetles ( Popillia japonica Nevmi. ) involved designing a 
 duster to meet the requirements of the tests. Briefly, it was necessary 
 to distribute amounts ranging from 0,U 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 l/l6-inch in diameter. A standard-pipe- size l/8-inch 
 tee (£) 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 tlie third tee opening, 
 which is directed vertically upward. All metal parts are of brass. 
 
 
 
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 A 
 
 
 mmmmm^wm^m 
 
 
 
 
 Figure 1. — Perspective drawing of duster. 
 
 i'The authors are indebted to G. J. Baetzhold, Division of Japanese 
 Beetle Control, for the drawing presented in this paper. 
 
 1348 
 
- 2 - UNIVERSITY OF FLORIDA 
 
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 3 1262 09240 9787 
 
 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 b** drawn from funnel E into tee £, 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.