Control of Farm Flies in Malta—II. Residual effectiveness of insecticide formulations on various surfaces toMusca domesticaandStomoxys calcitrans

Abstract

Bioassays were carried out under laboratory conditions to determine the residual toxicities to the housefly, Musca domestica L., and the stablefly, Sromoxys calcitrans L., of a range of insecticide formulations sprayed on wood, Maltese limestone, cement-washed and lime-washed stone. Stomoxys were more susceptible to all deposits than were Musca. Wettable powders were more effective than emulsions; some being still highly toxic to flies a year after spraying. Most formulations had a shorter life on stone than on wood but a covering of cement could extend the residual life markedly. With tetrachlorvinphos w.p. on stone, respraying nine weeks after the initial spraying resulted in higher kills and longer residual life following the second spraying than after the first.