Corn Flea Beetle: Expectations for Injury in 1999

April 2, 1999
A very small insect that causes some anxiety in the seed production business each year is the corn flea beetle. The flea beetle is named for its small size (1/16 inch in length) and its impressive leaping ability when disturbed. Flea beetles overwinter as adults and are most likely a problem when corn plants are slowed in their development by cool spring conditions. Of utmost concern to the seed industry is the potential for transmission of Stewart's disease or wilt to susceptible inbreds.

Entomologists have long reported that mild winters favor the survival of flea beetles and increase the potential 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.

In Table 1, Steve Hollinger, Illinois State Water Survey, has provided sums for this 3–month period for the nine Illinois crop–reporting districts. With the exceptions of northwestern and northeastern counties, flea beetle survival through the winter should have been very good in most areas of Illinois. Even in these northern counties, winter survival can be rated as moderate to good for flea beetles.

We encourage vigilant scouting for flea beetles this spring (even in northern Illinois) especially where sensitive inbreds to Stewart's disease will be grown. Rescue treatments should be considered if 10 percent of the seedling corn plants have flea beetle feeding injury and two to three beetles are found per plant. Insecticides labeled as rescue treatments for corn flea beetle control include: Ambush 2E,* Asana XL,* Lorsban 4E, Penncap–M,* Pounce 3.2 EC,* Sevin XLR Plus, and Warrior T or 1E.*--MG

(* Use restricted to certified applicators only.)

Table 1. Prospects for corn flea beetle survival by Illinois crop-reporting districts.
Illinois crop-reporting districtsSum of monthly temperature (deg F) averages for December, January, and February
Northwest 83.9
Northeast 86.9
West 93.3
Central 92.1
East 92.7
West southwest 100.1
East southeast 102.8
Southwest 112.1
Southeast 112.8

Author: Mike Gray