STUDIES ON NONARSENICAL STOMACH-POISON 
INSECTICIDES 1 
By William Moore and F. L. Campbell, Fruit Insect Investigations, Bureau of 
Entomology, United States Department of Agriculture 
NATURE OF THE STUDY 
In attempts to find a satisfactory insecticide for the Japanese beetle at River¬ 
ton, N. J., a rather hasty survey of possible arsenical substitutes was made, 
and many compounds too expensive for practical use were tested with the idea 
of helping to develop useful laws of insect toxicology, a subject exceedingly 
obscure at present. 
PROCEDURE 
Since the urgency of the situation would permit no loss of time over unpromis¬ 
ing compounds, the method of experimentation chosen does no more than indi¬ 
cate those compounds worthy of more exhaustive tests. All experiments were 
carried out in small cages; in summer, in the open air under a canvas shelter; 
in spring and fall, in a greenhouse. A certain number of insects, usually 20, 
were placed in a cage, and the sprayed or dusted foliage of either potted plants 
or freshly cut shoots, placed in water, was then introduced. In every case 
sprayed foliage was allowed to dry before it was placed in a cage. A record 
was kept of the compound used; its concentration, if used as a spray, in terms 
of pounds of the insecticide per 50 gallons of water; the number of insects in 
the cage; the number dead at the end of every 24-hour period after the start of 
the experiment until it seemed unnecessary to continue it; the percentage killed 
during seven days, or less, if the test was not run so long; the amount of feeding; 
and injury to the foliage by the insecticide. In some cases the number of insects 
that were on the floor of the cage stupefied was also recorded. The extent of 
feeding was recorded as “slight” if the area eaten was hardly noticeable, “heavy” 
if the feeding was about the same as that on the control plant, and “medium” 
if the amount consumed was between the two extremes. In a like manner 
foliage injury was recorded as “slight” if it could be detected only on close 
examination, “severe” if all the leaves were practically destroyed, and “medium” 
if the injury was partial. When the Japanese beetle was not obtainable, tests 
were made on the tent caterpillar (Malacosoma americana Fabricius), the Colo¬ 
rado potato beetle (Leptinotarsa decemlineata Say), and the squash lady-beetle 
(Epilachna borealis Fabricius). 
DISCUSSION OF EXPERIMENTS AND TABLES 
INORGANIC COMPOUNDS 
Table I shows the effect of certain relatively insoluble salts on the tent cater¬ 
pillar. The more soluble compounds were the more injurious to both foliage 
and caterpillar. Barium carbonate and barium oxalate were tested later on the 
Japanese beetle (Table II), but were without effect. As a general rule the beetle 
was more resistant than the other insects to the compounds tested. Antimony, 
though similar chemically to arsenic, was ineffective in both compounds tested. 
1 Received for publication March 17,1924. 
Journal of Agricultural Research, 
Washington, D. C. 
( 395 ) 
Vol. XXVIII, No. 4 
Apr. 26, 1924 
Key No. K-127 
