Abstract
The joint toxicities of pyrethroids were tested against the Takatsuki strain of the housefly (Musca domestica vicina). The co-toxicity coefficients of mixtures were calculated by using the Sun-method (1950). The co-toxicity coefficient of an insecticide-mixture [numerical formula] When the coefficient of a mixture indicates about 100, it showns similar joint action. If the coefficient is less than 100, it seems to be independent action. In the case of a significant value above 100, it indicates synergism. While it is significantly less than 100, it shows antagonism. The mixtures of chrythron plus allethrin and chrythron plus phthalthrin showed high synergistic action. Chrythron was more effective than allethrin and phthalthrin.
