... 23 - 
Weinman and Decker (48$) in Illinois conducted one-quarter acre 
plot tests against 3 species of grasshoppers, Melanot)lus differential is, 
M» fQm ur, rubrum (Deg.), and M. q exicanus . One pound of chlordane was 
about as effective as 2 pounds of toxaphene and was more rapid in action. 
Toxaphene showed a somewhat longer residual action than chlordane at rela- 
tively high dosages. The LD-50 values for chlordane against M. differen- 
tial is adults when tested for contact effect were l6.3 in 19*47 and 9.3 
in 1948; when tested for stomach-poison effect, the values were 21 .8 and 
12.. In these tests parathion and the gamma isomer of BHC proved more 
toxic and toxaphene and DDT less toxic than chlordane. There was some 
evidence of slight synergism in mixtures of DDT and chlordane. The 
greater the ratio of DDT to chlordane, the greater the synergism. 
Gaines and Dean ( 1.69. ) in Texas determined the relative toxicity of 
certain insecticides to first to third instar nymphs (M. d iffer ent ial i s ) 
when applied as contact sprays and dusts to be as follows: 
MLD. poun ds active ingre dient s per acre 
Treatment Spray emul sions Dust 
Toxaphene 1.17 1*73 
Chlordane *U$ 1.49 
Parathion .05 .17 
Benzene hexachloride .04 17 
Lindane .08 
, The materials applied as sprays made from wettable powders were as 
effective as when applied as spray emulsions made from miscible oil con- 
centrates. However, the dosages required to kill adults were consider- 
ably higher than those required to kill the first and second instar nymphs. 
In the field tests chlordane and toxaphene were approximately equal in 
toxicity to young grasshoppers when applied as spray emulsions. Dieldrin 
was more toxic to grasshopper nymphs than benzene hexachloride, chlordane, 
aldrin, or toxaphene. 
Chlordane was first tested against grasshoppers in the field in the 
summer of 194-6. A dust containing 5 percent of chlordane applied at the 
rate of 25 pounds per acre killed more than 90 percent of the grasshoppers 
in a Missouri apple orchard and prevented re-infestation for 30 days. — 
Wingo et al. (501,). 
Numerous field tests of chlordane against grasshoppers have been con- 
ducted in Argentina (Parker, 356 ). Canada (Putnam, 379 ) . South Africa, 
Australia, Salvador (Zuniga et al . . 52u5) » SXi ^- many of the states. The 
following report by Parker ( 357 ) « of the U. S. Bureau of Entomology and 
Plant Quarantine, of field tests made in Arizona, California, and Montana 
in 1947 presents results typical of those found by other workers. 
When applied in sprays or dusts, chlordane and toxaphene caused high 
mortalities within 24 hours and continued to kill over a period of 1 to 4 
weeks. Each of these materials was as effective in oil solutions as in 
emulsion and when applied from the ground as from airplanes. Chlordane 
at 1 pound per acre in such formulations reduced grasshopper populations 
