The present work was planned to evaluate the delayed effect of certain insecticides, cypermethrin, esfenvalerate, fenpropathrin, cyanophos, methomyl, diflubenzuron and Deenate on the eggs (1-3 days old eggs) and larval stages (newly hatched and 10- day old larvae of the pink bollworm, Pectinophora gossypiella (Saund.) and spiny bollworm, Ferias insu/ana (Boisd.). The following biological aspects were studied for the alive larvae after treatment:Larval duration, pupal duration, larval and pupal mortality percentages, pupal weight (mg.) and pupal reduction percentage. Delayed effect of insecticides were recorded as follows: pr-eoviposition, oviposition & post-oviposition periods, adult longevity, egg laying rate (no. of eggs/female), percentages of egg hatchability, control of hatchability, fecundity and sterility. Fenpropathrin: gave the highest effect on larval duration, pupal weight for male & female, adult longevity, post-oviposition period, egg laying rate, percentages of hatchability, fecundity and sterility. While, Deenate gave the highest delayed effect on larval and pupal durations, percentages of larval and pupal mortality, pre-oviposition and oviposition periods, percentages of egg hatchability, control of hatchability and sterility. The other tested insecticides caused intermediate delayed effect on the treated stages of PBW and SBW.