Reports of wireworms destroying crops have been rolling in from the fields. Wireworms are a hard-bodied brown worm that is the larvae form of the click beetle. They look very similar to meal worms. The adult click beetles burrow into the ground and lay their eggs near grass roots. This is why wireworms are commonly an issue in newly turned sod and/or weedy fields where grass is the primary species. Wireworms have a wide range of plants they like to eat but are especially destructive to corn. Corn fields attacked by wireworms will exhibit reduced plant populations and ultimately yield. The wireworms feed on the seeds prior to or just after germination. In addition, they can also bore into underground portions of the corn plant causing them to wither and die.
Wireworms are most often a problem in fields that have been in sod for many years or the second year following sod. They are generally an early season pest issue of corn. Wireworm infestations are usually noted in areas of a field that stay moist for long periods of time or when corn planted early is subject to cool and wet soil conditions. As soil temperatures warm, wireworms will begin to move deeper in the soil profile, eventually to where they are no longer a threat to the growing corn. With wireworms, there is no effective rescue treatment once symptoms of damage are observed. Therefore it is wise to either keep highly susceptible crops out of high risk areas, delay planting in high risk fields, or apply an approved insecticide treatment. There are several soil-applied or seed treatment insecticides that can give satisfactory wireworm control. Some natural controls, such as fungi and nematodes, may keep wireworm populations at tolerable levels. For a list of recommended insecticides, contact your local Extension office. Download a pdf version of this article.