482 



Davis (J. J.). Miscellaneous Soil Insecticide Tests. — Soil Science, 

 New Brunswick, N.J., x, no. 1, July 1920, pp. 61-72, 2 plates. 



The results of various experiments and observations with soil insecti- 

 cides are described. Experience with carbon bisulphide indicates 

 that its use against most species of Lachnosterna (white grubs) and 

 similar insects is impracticable, but that it is useful in destroying ant 

 colonies and in killing those grubs that hve in an open burrow, such as 

 those of Allorrhina {Cotinus) nitida (southern green June beetle). 



The efiect of kerosene emulsion on various grubs is recorded ; this 

 did not prove as satisfactory an insecticide as cyanide, being less 

 effective, more expensive and more difficult to make up and apply. 

 The same may be said of commercial preparations of coal-tar or creosote. 

 Corrosive sublimate proved ineffective in repeated tests. Sulphuric 

 acid was tried in various strengths against grubs of Popillia japonica 

 (Japanese beetle), but no apphcation gave more than 10 per cent, 

 mortality. Acetaldehyde was wholly inefiective in many tests with 

 the same species, and never gave a higher rate of mortality than 12 per 

 cent. Kopper's solution (a by-product containing approximately 25 

 per cent, carbon bisulphide and 75 per cent, benzine) in a number of 

 t3sts gave no higher mortality than 9 per cent. 



Important consideration was given to tests with sodium cyanide. 

 A brief review of previous work with this insecticide is given. In the 

 present experiments, for small areas such as lawns and gardens, an 

 ordinary sprinkling can was used, granular sodium cyanide at the rate of 

 1651b. in 12,000 U.S. gals, of water being used per acre. For larger 

 areas a 600-gaUon tank mounted on heavy wagon frames and drawn by 

 a caterpillar-type tractor was used. The results of these treatments 

 against P. japonica in various kinds of stubble and grass-lands are 

 recorded in a series of tables, and the methods of apphcation and the 

 labour and expense involved are described. The degree of mortaUty 

 shows great variation, averaging about 78| per cent, over 65 different 

 tests with various dosages. Ground covered with timothy grass, weeds, 

 or similar vegetation allowed better penetration of the insecticide if 

 the crop was closely mown, consequently a higher mortality was 

 obtained than where the vegetation was tall and matted. When the 

 cyanide was applied d«y and the treated area afterwards watered, 

 the results were uniformly poorer than when the cyanide was appUed 

 in liquid form. Where comparisons were possible it was observed 

 that cyanide was more effective against the grubs of Cyclocephala, 

 Lachnosterna, and Macrodactylus than against those of P. japonica, 

 the latter haA^ng apparently burrowed deeper than the other species 

 of beetles at the first approach of cold weather. 



Little is known of the efiect of cyanide treatment on soil. In the 

 present experiments it was found that grass might be scorched by the 

 cyanide solution, but the injury was not permanent except where the 

 liquid stood in low places for a considerable time. Cultivated crops, 

 such as maize, were appreciably injured by the treatment. The 

 chemical effect on the soil, and on dift'erent kinds of greenhouse plants 

 when treated soil is used for potting and seed-beds, requires further 

 study, and the whole question of cyanide treatment has as yet been 

 so little investigated that only fragmentary results and temporary 

 conclusions have been attained. 



