February,'22l moore: Japanese beetle poisons 67 



THE REACTION OF THE JAPANESE BEETLE TO ARSENICAL 



SPRAY DEPOSITS^ 



By William Moore, Riverton, N.J. 



Several years' experience with the Japanese beetle {Popillia japon- 

 ica Newm.) has demonstrated that the adult beetles are "repelled" 

 from tbe foliage of plants sprayed with arsenicals. Within one or two 

 hours after spraying, most if not all of the beetles which had been 

 present on the plant, have disappeared. During the summer of 1920 

 and the first portion of the season of 1921, Leach and Brinley con- 

 ducted experiments which show that this reaction of the beetles is not 

 due to the color, the discontinuity, or tbe thickness of the spray deposit. 

 The beetles will readily eat plants sprayed with white barium car- 

 bonate or lime, black lampblack, orange antimony trisulphide, or 

 greyish brown clay. Clay or lime with coarse size particles was con- 

 sumed but lead arsenate, ferric arsenate, and zinc arsenate, having in 

 some cases particles so small that the spray deposit could no longer 

 be distinguished on the foliage, acted as repellents. 



A crude ferrous arsenate was reported by Davis- as having an at- 

 traction to the beetles, but the material was found to be non toxic. 

 During the summer of 1920 it was shown that ferrous arsenate precipi- 

 tated by the use of tri-sodiiun arsenate was readily eaten by the beetle 

 but proved to be non toxic in cage experiments. Ferrous arsenate 

 precipitated with tri-sodium arsenate contains some ferrous hydroxide 

 which changes over to ferric hydroxide, an antidote for arsenical poison- 

 ing. Basic lead arsenate was also found to be eaten by the beetles, 

 but so late in the season that a toxicity test was impossible. In the 

 early part of the season of 1921, basic lead arsenate was tested and 

 found to be practically non toxic to the Japanese beetle. 



During the season of 1921 an effort was made to discover why the 

 beetles leave the sprayed plants. Field observations have shown that 

 beetles will feed for a short time upon plants sprayed with acid lead 

 arsenate, ferric arsenate or zinc arsenate, but leave before they have 

 consumed a killing dose. From time to time new beetles will come to 

 the sprayed plants and start feeding, but they also leave before con- 

 suming a killing dose. Beetles collected from such plants, and placed 

 in a cage with an unsprayed food plant have lived and acted normally 



^Published' by permission of the Secretary of Agriculture, U. S. D. A. anr* the 

 New Jersey Dept. of Agriculture. 



^Davis, J. J., "The Green Japanese Beetle Problem", Jl. Econ. Ent., Vol. 13, No. 

 2, April, 1920. p. 194. 



^The statements made in the above introductory portion of the paper are largely 

 aken from the unpublished notes of Leach and Brinley during the summer of 1920 



