University of Illinois

No. 4/April 17, 1998

Corn Flea Beetles: Watch Out for These Insects This Spring

Corn flea beetles will likely create some anxiety this spring for those involved in the seed-production business. Flea beetles are quite small (1/16 inch in length) and are impressive leapers when disturbed, so their name is a good fit. Flea beetles overwinter as adults and are most likely a problem when corn plants are slowed in their development by cool spring weather. Of primary concern to the seed industry is the potential for transmission of Stewart's disease or wilt to susceptible inbreds.

Corn flea beetles on seedling corn plant.

Mild winters favor the survival of flea beetles and increase the odds that Stewart's disease may be a problem. In an effort to quantify the effect of winter conditions on beetle survival, it is commonly suggested that if the average monthly temperatures for December, January, and February sum to more than 90, flea beetle survival through the winter may be good.

Bob Scott, Illinois State Water Survey, has provided a map (Figure 1) for Illinois that reveals winter temperatures for this 3-month period will favor the likelihood of increased problems this spring with flea beetles, for essentially the entire state. We encourage vigilant scouting for these small beetles this spring, especially where inbreds and hybrids susceptible to Stewart's disease are being grown. Insecticides labeled as rescue treatments for corn flea beetle control include *Ambush 2E, *Asana XL, Lorsban 4E, *Penncap-M, *Pounce 3.2EC, Sevin XLR Plus, and *Warrior 1EC (* = use restricted to certified applicators only).

Figure 1. Sum of monthly average temperatures for the months of December 1997 to February 1998.

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