Insecticide resistance in houseflies from two sites in Southern Africa

Results of a recent study conducted by the Wellcome Research Laboratories, Berkhamsted, U.K. in to the insecticidal resistance in strains of houseflies collected from South Africa and Zambia are discussed. Both straines were very resistant to the insecticides commonly used in their respective localitites, namely bromchlorphos and trichlorphon. Interestingly, the results are also show housefly resistance to many other compounds with which they had not previously been in contact. The pyrethroids, however, emerged as the only chemical group to which the houseflies remained fully susceptible