Plodia interpunctella (Lepidoptera:Pyralidae) by Doug Johnson,
Extension Entomologist University of Kentucky College of
Agriculture Indianmeal moth larvae are secondary pests, which
means that they prefer to feed on fines or damaged kernels.
Infestations are most common in the upper four to six inches of
grain in a bin. They become active in early spring because
surface grain is usually the first to warm. The larvae produce
silken threads which result in "caking" or "crusting" of the
surface grain. Their frass (waste), cast exoskeletons (exterior
skin-like covering) and silk contaminate the grain. Indianmeal
moths (pictured left) rest with their wings folded over their
backs. They are about 0.4 inch long with a wingspan of about 0.6
inch. The outer portion of the front pair of wings is coppery;
however, this color may be lost as the moth loses its scales.
The inner half of the wing near the body is light gray. The hind
wings are gray with no distinctive markings. The larval or
feeding stage is a caterpillar (