Toxicity of individual pyrethrin esters to house flies (Diptera : Muscidae)

Six pyrethrin esters were separated from whole pyrethrum by using high perf ormance liquid chromatography on a silica column. Dilutions of individual e sters were applied topically to house flies (Musca domestica L.) and compar ed to whole pyrethrum and transpermethrin. LD50's averaged from two signifi cant dosage-mortality regressions per chemical were in ascending toxicity: Cinerin 1 (1.77 mu g/fly), jasmolin 1 (1.28 mu g/fly), pyrethrin Il (0.49 m u g/fly), jasmolin 11 (0.46 mu g/fly), cinerin 11 (0.43 mu g/fly), pyrethri n 1 (0.20 mu g/fly), 25% pyrethrin extract (0.11 mu g/fly) and trans-permet hrin (0.0072 mu g/fly).