Insect Pests

Japanese beetles are easy to distinguish by their coloring and tufts of white along their sides.- Clemson University USDA Cooperative Extension Slide Series, www.insectimages.org

Most gardeners know Japanese beetles from their attacks on roses, fruit, and lawns. However, the beetles also love corn, asparagus, and rhubarb.

The life of Japanese beetles is complex. In the ground they are white grubs, best known for eating the roots of lawn grass, but they also attack the roots of corn, which is a type of grass. When adult beetles emerge from the ground in late spring and summer, they begin feeding on their favorites leaves and flowers. You can dust corn plants with Sevin to reduce beetle numbers, but because they fly in hordes from far away, the battle can seem futile. Fortunately, "beetle season" passes in summer as the adults die of old age. However, a new generation of grubs is feeding in grass or elsewhere underground, preparing to return next year.

There are biological controls (parasitic nematodes, Bt, and others) that you can apply to the lawn to help reduce the population next year. Often neighbors get together to treat whole neighborhoods because the beetles can fly such long distances. For more information about an integrated pest management approach to controlling Japanese beetles, contact your local county Extension office. A Google search for Japanese beetles on corn in your state will also bring up plenty of information about control techniques recommended in your area and their timing.