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Issue No. 3, Article 3/April 23, 2010

Black Cutworm Moths Have Arrived, Including Northern Illinois Counties

With the record warm weather in April fueled by strong southerly breezes, we shouldn't be too surprised with the recent captures of black cutworm moths in pheromone traps. University of Illinois crop systems extension educators Dale Baird, Greg Clark, Bill Lindenmier, and Jim Morrison all reported early moth captures (April 1 to April 14) in Lee, Whiteside, Ogle, and Winnebago counties, respectively. So far no intense captures (9 or more moths caught over a 1- to 2-day period) have been reported to me. After 300 heat units (base 50°F) have been accumulated from this biofix, cutting of corn plants can begin to occur (Table 1).

By using our insect degree-day calculator, you can input when an intense capture of black cutworm moths has occurred in your area; then, with the use of historical temperature data, you can predict when cutting of corn plants may begin to occur. This web page outlines scouting procedures and life cycle features of the black cutworm.

A final cautionary note--don't assume that just because you planted a Bt hybrid you are no longer at risk for an infestation of black cutworms. Heavy infestations have proven problematic in some Bt cornfields. Be prepared to scout corn for this insect and apply a rescue treatment as needed.--Mike Gray

Mike Gray

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