University of Illinois

No. 9/May 23, 1997

More Reports of Corn Flea Beetle Activity

Corn flea beetles continue to have an impact on corn production in some areas of southern Illinois. On May 19, a producer in Clay County indicated that he was applying a rescue treatment to a cornfield in which flea beetles were the most numerous he had ever seen. The grower pointed out that densities of 10 or more beetles per plant were common. Producers in Effingham and Fayette counties also reported finding on a regular basis 3 to 5 beetles per plant and occasionally as many as 7 to 8 beetles per plant.

Corn flea beetle, injuring corn seedling.

We have discussed flea beetles twice in this year's Bulletin (issues no. 2 and 8); and, as long as the pattern of cool weather continues, we expect reports of flea beetle injury to persist. Of interest are a few additional flea beetles facts (Metcalf, Flint, and Metcalf, 4th edition, 1962) that we may not have mentioned in earlier issues of the Bulletin.

€Various species of flea beetles are worldwide in their distribution.

€Many kinds of plants are fed upon by flea beetles, including millet, sorghum, broom corn, sweet potato, sugar beet, oats, morning-glory, bull nettle, and cabbage.

€Cornfields that are kept free from weeds (internally and at the field margins) are less likely to have problems with flea beetles.

€Corn flea beetle larvae often feed upon the roots of weeds, emerge as adults, and begin feeding on the leaves of seedling corn plants.

€Early planted cornfields are more susceptible to flea beetle injury than later-planted fields.

Mike Gray, Extension Entomology, (217)333-6652