Microctonus aethiopoidesLoan, developed from alfalfa weevils treated with LD50to LD90dosages of carbofuran (Furadan®), methyl parathion, methoxychlor and methidathion (Supracide®), during egg, early larval and late larval stages of parasite development did not differ significantly from the controls in reproductive potential, longevity and progeny sex ratio. However, parasites which survived LD50dosages of these insecticides during adult or pupal stage showed a 25–50% reduction in longevity and 40–60% reduction in reproductive potential. Sex ratio of the progeny again remain unaffected.