LC50values were determined for six populations (two laboratory and four wild-type) of Indianmeal moth,Plodia interpunctella(Hübner), to peroral inoculations of a granulosis virus. Various biological parameters of the populations were measured to determine similarities or differences among the moth populations tested. A significantly (P<0.05) higher LC50value was measured for two of the wild-type populations (one from the west coast and one from the east coast) compared with the others. These two populations also had significantly (P0.05) different among them, but showed them to be more susceptible to the virus and with shorter developmental times compared with the two wild-types discussed above.