Studies on bionomics and chemical control of the American cockroach, Periplaneta americana L., in Hashima Island, Kyushu, Japan

Abstract

The bionomics of American cookroach, Periplaneta americana, was investigated in the apartments in Hashima Island, Kyushu, Japan, and the experiments on the control of the roaches by the application of four kinds of insecticides were also done in the same apartments. The results were summarized as follows : In Hashima Island, P. americana was the dominant species of the roaches, the bionomics of which had scarcely been reported in Japan except a few records on the local distribution, and the other species found were P. fuliginosa and Blattella germanica, both of which were far less than P. americana. Male roaches were more abundantly found than the female ones. The roaches were found to be distributed in the apartments not evenly but concentratedly to the particular sections, where kitchinranges would often be used and firewoods and the other materials were disorderly kept under the kitchinranges, or highly moisty. The spray of insecticidal emulsion directly to/or near the hiding places of the roaches were more effective than the coating of the emulsion on the corners or the edges where the roaches would often crawl. The most effective methods were the spray of 1% lindane emulsion and the mixed emulsion of 0.4% dieldrin and 0.6% lindane. The spray of 1% diazinon emulsion was comparatively effective and the effect of 1% BHC suspension was lower than the chemicals stated above. However, about 30 days after the application of any insecticides adopted there, the population of the roaches was found to recover to the level before the application. By the application of the insecticides, the ratio of larvae to all the roaches and that of the male to all adult roaches decreased, probably because of higher susceptibility of larvae than adults and of the male than the female. Thus, it caused the increase of the ratio of female roaches to all the roaches. The fog application of 9.2cc of 0.3% DDVP solution per square meter of floor were practically ineffective to American cockroaches.