The corn plant Zea mays L. plays host to a variety of insect pests. Among the most important of these are the western corn rootworm beetles and the European corn borer. Crop losses and control costs associated with these pests run into the millions of dollars annually.

Corn rootworm (CRW) beetles exhibit a univoltine life cycle. Feral adults deposit their eggs into the soil of cornfields during July and August where they undergo diapause and overwinter. The following spring eggs hatch beginning in late May and continuing on into the middle part of June. Larvae of the new generation feed on developing corn roots. After reaching the third instar larvae pupate in the soil, and emerge as adults during June and July. Adults live between 75 and 85 days and feed on pollen, silks, and leaf material. Damage occurs as roots from corn plants are fed upon and pruned by larvae. This eventually hinders the plants’ ability to uptake water and nutrients. Extensive root damage may also cause plants to lodge (fall over), resulting in yield losses and an increased harvesting time.

The European corn borer (ECB) is a foreign pest introduced to the North America in 1912. Since its arrival this insect has hindered corn production throughout the major growing regions of the US and Canada. The ECB exhibits a bivoltine (2 generations per year) lifecycle in southern Wisconsin and the majority of the Midwest. ECBs overwinter as fifth instar larvae, and emerge during mid to late June. Adult females of the first generation mate and deposit masses of 15-25 eggs into the whorls of developing corn plants. Following egg hatch larvae feed on corn pollen, ear silks, and leaf tissue. As the larvae mature they begin to bore into the stalk or leaf midrib of the plant. Tunneling larvae continue to feed and develop inside the plant and eventually pupate. Adults emerging from these plants commonly mate in grassy areas near the field margins, and return to lay eggs on the leaves of corn near the pollenation stage. Larvae of second generation ECBs feed on sheath collar and leaf tissue before tunneling into leaf midribs, ear shanks, and stalks. The second generation continues development until early to mid fall when the larvae undergo diapause. Damage from ECB feeding results in broken stalks, dropped ears, and physiological damage. Larval tunneling can inhibit the plants ability to uptake water and nutrients which results in yield losses due to small ears and a general reduction in plant growth.