Soil degree day accumulation as of 14 June 2013.
This egg hatch prediction is behind the average date of 6 June and way behind numbers for 2012. People that track egg hatch in Indiana and Illinois also reported delayed egg hatch, due in part to the extreme drought in 2012. Mike Gray, Illinois extension entomologist, said sometimes females will lay eggs deeper into the soil profile in drought conditions. The delayed corn planting throughout much of Iowa means larvae will have a smaller root system to feed on and potentially damage. I've also had people ask me about saturated soils killing rootworms this year. It is possible to suffocate the larvae, but the eggs probably survived water-logged soil.
I encourage all you scouts and farmers to check your corn roots mid July to assess any corn rootworm injury. It will help determine the ongoing strategies for this unruly beast. Unexpected corn rootworm is possible with all Bt traits in continuous corn production. To read more about corn rootworm management, read this short ISU publication Aaron Gassmann and I wrote over the winter.