Source: Iowa State University
Although some believe that the appearance of lightning bugs (fireflies) correlates with corn rootworm larval hatch in the Midwest, Marlin Rice, former ISU entomologist, and Mike Gray, entomologist from University of Illinois, say the two events are unrelated. They say corn rootworm hatch predictions are more accurately based on temperature accumulations.
Research shows about fifty percent of corn rootworm larvae will hatch from 684 to 767 accumulated growing degree days (base 52 F). Corn rootworm hatch should be happening in the southeast part of the state. Other parts of the state should experience larval hatch in the next seven days.