The larvae of the corn earworm come in different colors, ranging from light green to pink to dark brown or black. Light and dark stripes alternate down the body. Tubercles are present with two or three large hairs each. There are five growth stages and end up at 1½ inches long at maturity.
Their eggs are laid singly on the preferred food plant leaves, such as fresh-silking corn, and occurs 3 days after emergence. The eggs are ribbed, hemispherical, and less than 1/16 inch in diameter. After 24 hours, the eggs develop a red ring around their white exterior and will show the black head capsule just before hatching. Each egg will take 3 to 4 days to hatch. Newly hatched larvae will feed on the host plant, typically the reproductive structures. These larvae are not initially cannibalistic, however will grow to become more aggressive and kill other larvae over time. The pupa are about ¾ to 1 inch in length and are reddish or light brown. They call soil home near the host plant and can be as deep as 6 inches. Pupal stage is about 13 days. Adults are nocturnal moths that are about ¾ inch long with a wingspan of 1½ inches. Dark lines or spots decorate the tips of the yellowish tan forewings. The hindwings are whitish with dark grey veins and border.
During daylight, the moths may hide in vegetation or feed on nectar. A healthy female can lay between 500 to 3000 eggs, and can produce up to 35 per day. They have several broods from May to December and can be found throughout North America except for Canada and Alaska. The corn earworm does not overwinter successfully in the north-eastern United States. It is most active in tropical and subtropical climates. Their life cycle can be completed in as little as 30 days.
Written by: Christian Newkirk, an undergraduate Environmental Science student at the University of Oklahoma