Corn Rootworm Egg Hatch: An Update

May 28, 1999
Corn rootworm eggs should be hatching the last week of May across much of central Illinois. When 380 to 426 heat units (base 52°F) have accumulated (since January 1), as many as 50 percent of the corn rootworm eggs should have hatched. Figure 1 reveals that as of May 24, between 300 and 400 heat units (base 52°F, 4-inch soil temperature) had accumulated since January 1 across a broad band of central Illinois. After you return from the Memorial Day weekend, don't be surprised if you begin to hear of reports of rootworm feeding. The first instars will be quite difficult to find since they are primarily internal root feeders. Overall, establishment of corn rootworm larvae is expected to be much better in most cornfields this spring. For those producers whose fields received heavy precipitation, if standing water is present, corn rootworm larval survival will be very poor. Let us know when you discover your first corn rootworm grub of the season.--Mike Gray

Author: Mike Gray