Abstract
Quantitative and qualitative work on the resistance of houseflies to γ‐BHC is described, in which BHC isomers labelled with ^36^Cl or ^14^C were used. α‐, β‐, γ‐ and δ‐BHC are converted to water‐soluble compounds by houseflies, the α‐ and γ‐isomers being more susceptible to the conversion than the β‐ and δ‐compounds. The reaction in the cases of α‐, γ‐ and δ‐BHC is accompanied by production of chloride ions corresponding to the removal of 4 to 6 atoms of chlorine from each molecule of BHC metabolized. It is therefore considered unlikely that the metabolites are trichlorobenzene derivatives. Chromatographic evidence indicates the ultimate production of eleven water‐soluble compounds from both α‐ and γ‐BHC. It is deduced from two‐dimensional chromatograms and from paper electrophoresis that the two isomers produce an identical or very similar series of compounds and that these are acidic. The role of metabolism in defending the insect against poisoning is discussed in terms of concentration X times effects and it is concluded that detoxication by metabolism is essential for the complete recovery of the insect following absorption of insecticide. Measurement of the capacity of a number of susceptible insect species to metabolize BHC isomers shows that the susceptible strain of housefly exhibits exceptional ability to eliminate γ‐BHC as water‐soluble products.