Measured Dose of Gamma Hexachlorocyclohexane ( 666) Required to Kill Flies and Cockroaches, and a Comparison with DDT

Abstract

The approximate LD-50 for 7666 in the cockroach (Periplaneta americana) is 4.6 mg. per kg. when applied to the body surface and 3.4 mg. per kg. when injd. in-tra-abdominally. These values are not significantly different. An approx. equivalence, similar to that noted above, between surface and injn. toxicity for the roach has been reported for DDT. This finding emphasizes the importance of the absorptive capacity of the insect body surface for contact poisons in contributing to the effectiveness of insecticides. The approx. LD-50 for 7666 applied to the body surface is 0.4 mg. per kg. for the newly emerged fly Musca domestica. For the older adult the LD-50 is about 0.8 mg. per kg. for M. domestica and 0.6 mg. per kg. for Calliphora spp. This decrease in sensitivity as the fly ages is less than that reported for DDT. Gamma 666 is about twice as toxic as DDT for the cockroach (P. americana), and is distinctly more toxic than DDT for flies. Both death and knockdown occur more rapidly after surface application of [gamma]666 to the fly and cockroach than after DDT.