Abstract: The efficacy of acetone vapors against carefully aged eggs of Plodia interpunctella (Hubner) at 17±1 and 27±1°C at different dosage levels of acetone over various exposure times was determined. Acetone was found to be toxic to Indian meal moth eggs. Considerable variation in the susceptibility of different age groups of eggs was apparent in the fiducial limits of the LD50 values. An inverse relationship between LD50 values and exposure times was observed in age groups of tested eggs. At 27±1°C and 24 h exposure period, eggs aged 1-2 day-old were more tolerant to acetone than other age groups, followed by 0-1 day-old, 2-3 day-old and 3-4 day-old eggs. A similar pattern of susceptibility of eggs was observed at 72 h exposure. In all bioassays, eggs exposed to higher dosages of acetone 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 acetone. At 27±1°C eggs of P. interpunctella were killed by less than one-third of the dosage required for control at 17±1°C. Acetone achieved 50% mortality with a dosage of 82.76 mg L-1 in 1-2 day-old eggs at 27±1°C. At this temperature hatching was retarded and greatly diminished when eggs aged 1-2 day-old were exposed to 80 mg L-1 of acetone 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.