The eggs are glued to the kernel. Larvae emerging from the eggs eat through the kernel and begin feeding on the endosperm or germ. To assist in penetrating the kernel, larvae sometimes spin a cocoon that they use for leverage. Once inside the kernel, larvae continue to feed until mature, enlarging a cavity within the kernel. Larvae then spin silken cocoons and pupate within the kernels.
Adults emerge by pushing the flap back on the kernels.
The life cycle is complete in about five weeks at optimal temperatures. The front wing is a lighter color than the hind wing. Both wings end in a thumb-like projection and have fringed rear margins. The eggs are white when first deposited, but soon turn red. Full grown larvae are one-fifth inch long and white with a yellow head.