Abstract
Seven strains Musca domestica L., including one susceptible strain, were tested with a wide range of organophosphates and carbamates. The results of these tests gave a broader picture of the patterns of cross resistance in strains that had been studied by previous workers and in addition showed two new types of resistance machanism, one possibly and oxidation mechanism, and the other possibly a modified AliE giving low levels of resistance to organophosphates and carbamates. This work also demonstrated the existence of at least three resistance machanisms for carbamates, two probably oxidative and the others minor machanisms associated with modified AliE.