When Will Rootworm Larvae Hatch? May 10, 2002 It's unlikely that we will experience an early hatch of rootworm larvae from overwintering eggs this year. Western and northern corn rootworm eggs have a developmental threshold of 52 deg F. Approximately 380 to 426 accumulated degree-days are required for 50% of the larvae to hatch. As you can see in Figure 3, degree-day accumulations (base 52 deg F), from January 1, at the 4-inch level in soil, are not far enough along for us to encounter rootworm larvae anywhere except extreme southern Illinois, where little corn has been planted. So, we'll wait and watch. It's possible that the soggy soil conditions will have a negative impact on rootworm larvae when they do hatch. Let's keep our fingers crossed.--Kevin Steffey Author: Kevin Steffey

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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