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53

SUMMARY

Tests to determine both residual action and initial kill of aldrin, chlordane, dieldrin and heptachlor were conducted at three separate dosages under variable outdoor insectary and controlled greenhouse conditions, and with limited field tests using single dosages of granular formulations.

All chemicals used in the field tests showed highly effective results although distinct differences did not exist between them. Initially, the quickest kill was obtained with heptachlor and dieldrin, but at the end of six days, the results of all four chemicals were comparable.

Laboratory experiments revealed that dieldrin was the most effective in producing the highest kill, and was followed by aldrin, heptachlor and chlordane in descending order of effectiveness.

As far as residual life is concerned, dieldrin ,surpassed all others, followed by aldrin and chlordane. The shortest exposure time was needed with heptachlor and aldrin. Chlordane was the weakest in this respect.

It was found, however, that in order to accurately judge the effectiveness of any particular one of these chemicals in relation to all or any of the others, consideration of the atmospheric conditions, the life stage of the earwigs, and the length of time that earwigs were in direct contact with the chemical, was a necessity.