Oxygen free radicals are generated as a by-product during normal metabolism, and they cause damage to proteins, lipids, and DNA in organisms. The defense system of the body counteracts these highly reactive chemical moieties and neutralizes them. However, a small fraction of free radicals escapes, which causes lipid peroxidation and hence aging of the organism. It has been hypothesized that, if the free radicals are arrested/reduced, then aging can be delayed or life span could be enhanced. To test the above hypothesis, we fed butylated hydroxy anisole (BHA) to a drosophilid insect, Zaprionus paravittiger, and observed its effect on life span, fecundity, and developmental period. The insects were reared and maintained on standard corn meal agar (CMA) medium at 26 degrees +/- 2 degrees C. Various concentrations (1, 5, 10, 25, 50, and 100 mM) of BHA were mixed with CMA medium, and the cultures were reared and maintained on these mixtures to study the life span of insects. Survivor curves showed that lower concentrations (5, 10, 25 mM) of BHA increased the life span, while higher concentrations (50, 100 mM), which were rather toxic, decreased life span. The most suitable concentration was 10 mM, which increased median (LT50) (27% and 15% in male and female) and maximum (LT100) (18% and 27% in male and female) life spans of insects maximally. Females exhibited longer life spans compared with males. The cultures were fed on the optimal concentration (10 mM) of BHA to study its effect on developmental period and egg-laying rate. The total developmental period was delayed by 7.2%, and egg-laying rate was reduced by 19.7% on BHA feeding. The extension in developmental period and reduction in egg-laying capacity could be the contributory factors to the favorable effect of BHA on life span.