This year's corn rootworm hatch -- at least in central Illinois -- may be right around the corner, says University of Illinois Extension entomologist Mike Gray.

Degree-days is the best way to estimate when the rootworm hatch will happen; Gray says about half of the hatch happens when 684 to 767 degree-days have built up since the first of the year.

Gray says the state of Illinois shows between 400 and 600 degree-days since January 1, with the latter number more common in the central part of the state and lower numbers further north.

The timeframe for the rootworm hatch (which has not been reported in other Corn Belt states yet), if it comes a little later this summer, may prove the efficacy of Bt corn against the pest, Gray says in a university report.

"If the hatch occurs later than predicted over the next several years, we may begin to build a body of evidence that suggests we may be selecting for corn rootworm larvae that hatch later due to the extensive use of Bt corn hybrids," he says.

This year's corn rootworm hatch -- at least in central Illinois -- may be right around the corner, says University of Illinois Extension entomologist Mike Gray.