Female moths are attracted to the tallest corn fields for egg laying. Eggs are laid in masses resembling overlapping fish scales on the underside of corn leaves. When eggs are laid on young corn, before six leaf stage, most larvae fail to develop. After the 8 to 12 leaf stage more larvae survive. During the whorl stage, larvae move into and feed in the whorl until the tassel begins to emerge.
Large larvae move down to the base of the corn plant and bore into the stalk before pupating there.
First eggs are expected at 450 to 500 degree days, base 50. Snap beans and peppers are not at risk until fruit begins to form. Growers should check sweet corn after the 8 to 10 leaf stage for eggs and larval damage. Treatment is recommended if larvae are found on more than 10 to 15 percent of the plants. Treatment at this stage should be directed down into the whorl Colorado potato beetle on volunteer potatoes Beth Bishop Walter Pett Ed Grafius Entomology Colorado potato beetle adults, eggs, and small larvae have been reported from several locations throughout Michigan.