Abstract: The effect of acrolein vapors against carefully aged eggs of Indian meal moth at 27±1 and 17±1°C at different dosage levels of acrolein over various exposure times was determined. Considerable variation in the susceptibility of different age groups of eggs was apparent in the fiducial limits of the LD50 values. At both temperatures and 24 h exposure period, eggs aged 1-2 day-old were more tolerant to acrolein than other age groups. In all bioassays, eggs exposed to higher dosages of acrolein developed at smaller rate. This was significant for the eggs, which were exposed to the highest dosage for 24 h. Increasing the temperature from 17±1 to 27±1°C greatly increased the efficacy of acrolein. Overall, at 27±1°C eggs of P. interpunctella were killed by less than one-fourth of the dosage required for control at 17±1°C. Acrolein achieved 50% mortality with a dosage of 3.80 mg L-1 in 1-2 day-old eggs at 27±1°C. At this temperature hatching was retarded and greatly reduced when eggs aged 1-2 day-old were exposed to 32 mg L-1 of acrolein for the 24 h exposure period. There was no evidence of a hatch delay longer than the time spent under vapors for eggs exposed at 17±1 or 27±1°C, indicating that some development must have occurred under fumigation.