Are the Green Bugs on My Corn Plants Aphids?

Identification

• Aphids are small insects, usually less than 1/8 inch long. They are soft-bodied and oval or pear-shaped. They occasionally have wings but are more often wingless. Their color varies, ranging between pale yellow-green and blueish or grayish green. Aphids may appear in groups of a few dozen or a colony of thousands can be part of a severe infestation. Take a sample insect to your nearest university extension office for identification. You also can access a number of insect identification guides online (see Resources).

Damage

• Corn leaf aphids are the most common variety to plague corn plants; they typically are found under leaves and whorls and on unemerged tassels. They have piercing mouth parts and feed on corn leaves and stems by extracting juices. Corn root aphids, another variety that commonly affects corn crops, feeds in a similar manner on plants roots. Aphids can cause stunted growth and reduced yields in severe cases, but generally do not cause significant harm. They excrete a sugary waste called honeydew that can lead to growth of black mold.

Management

• In most cases, no action is needed against aphids. They are often resistant to pesticides, and using pesticides can be detrimental as it kills many of aphids' natural predators. Even in cases where pesticides do reduce the numbers of aphids, it will not stop the spread of diseases they may carry. The best management for aphids is to encourage insects that feed upon them, such as ladybugs, lacewings and syrphid flies. Thoroughly removing weeds before you plant corn can also reduce the likelihood of aphid infestations.

Other Pests

• If you have small green insects on your corn plants, aphids are the most likely culprit, but a number of other pests are also possible. Corn rootworms can damage corn in some parts of the country. The larvae mature into beetles that feed on silks and pollen. Adults vary in color, but are usually green, yellow, black, or some combination on those colors. Corn beetles of several varieties attack corn by eating holes in the leaves; their color is generally bronze or blue green and they have a rounded appearance and enlarged hind legs that allow them to jump like fleas. Green stink bugs and Southern green stink bugs are shield-shaped, about 1/2 inch long, and sometimes feed on the ears of corn.