Corn rootworm egg hatch in Iowa typically occurs from late May to the middle of June, with an average peak hatching date of June 6. In 2015, the average hatching date will be slightly behind normal and approximately the same time as in 2014. Development is driven by soil temperature and measured by growing degree days. Research suggests about 50 percent of egg hatch occurs between 684-767 accumulated degree days (base 52°F, soil). A few areas of Iowa have reached peak corn rootworm egg hatch (Fig. 1), particularly around Muscatine. Many other regions will be reaching 50 percent egg hatch within 7-10 days.
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