A single female pantry moth lays between 100 and 400 eggs over a period of one to 18 days. Indian meal moths lay eggs in or near foodstuffs. According to a report published in the Journal of Stored Products Research, pantry moths lay eggs in areas with strong food smells and the presence of food-related oils. Foodstuffs left in barrels, poorly constructed containers or torn packaging are more likely to attract egg-laying moths. Pantry moth eggs hatch in two to 14 days.
Pantry moth larvae begin constructing white, silky tunnels immediately upon hatching. The maggotlike larvae live in these tunnels until reaching maturation and use them to access food. Pantry moth larvae cannot chew through packages, though they can pass through any aperture larger than a quarter millimeter tall or wide. The young moths have difficulty penetrating grain and other tightly packed foodstuffs deeper than one or two inches. The larval stage constitutes the majority of the insect’s life and lasts from two weeks to a full year.
Upon reaching maturation, pantry moth larvae spin cocoons in the walls of their habitat, be it a grain barrel or a pantry. Chrysalis takes four to 30 days. Mature brown moths emerge from the cocoon and stay within the habitat of the larvae while searching for a mate. The sole purpose of the mature pantry moth is to lay eggs. Adult moths live for only five to 25 days, just long enough to fertilize eggs in the case of male moths and lay eggs in the case of female months.
The full life cycle of a pantry moth lasts from 27 days to a little more than a year. As many as eight generations of pantry months may exist in a single calendar year, though the insects cannot survive cold weather. In most regions, winter severely limits the potential for successive generations. Temperature affects the length of the pantry moth life cycle. Moths in regions with temperatures of 86 degrees and higher generally complete a full life cycle in about half the time it takes moths in regions with temperatures of or around 68 degrees Fahrenheit. Moths express lethargy in temperatures less than 50 F.