1965 Volume 16 Issue 4 Pages 303-306
The biological and chemical analysis tests were conducted on adult houseflies to determine the residual effect of 0.3% DDVP oil solution fumigated in a room. The fumigation was done at the rate of 1ml per 1m^3 in the room where a veneer testing board was installed. The room was sealed for one hour after fumigation, and then the testing board was removed for testing. Houseflies of Takatsuki strain were continuously exposed to various surfaces of the board after two hours, three days, and six days of fumigation respectively and the time-knockdown data were observed. The residual deposit of the veneer testing board in two hours after fumigation was the most effective when it was placed at 5m distance from the jet nozzle and so the effect was most excellent when the surface faced vertically to the nozzle and in the descending order of the horizontal surface and parallel surface. The venner board in three days after fumigation showed an insecticidal effect on the surface facing vertically to the jet nozzle as well as on the horizontal surface at a distance of 5m. Even six days after fumigation, the insecticidal effect was confirmed on the surface facing vertically to the nozzle at 5m distance. Whereas the residual effect retained on the veneer board which was installed on the ceiling at 10m distance from the jet nozzle was noticeable for three days. However, the residual effect on the surface of a glass plate placed beside the veneer board was not recognizable. In case of substituting the testing board which was installed vertically to the jet nozzle at 10m distance for other ones, the insecticidal effect varies in the descending order of the painted veneer ≧ plain veneer > fiber board > textured board > polyvinyl chloride plate > mortared board. It is surmised from the above results that the fumigation of 0.3% DDVP oil solution gives to the indoor ceilings and walls the insecticidal deposit sufficient to kill houseflies.
