University of Illinois

No. 9/May 23, 1997

Black Cutworm Migration Update

Black cutworm moths were caught throughout Illinois during the monitoring period of May 10 to 16. Moths were captured in 24 counties, with intense flights reported in five counties on the following dates: Hancock (5/14), Logan (5/15), Macon (5/14), Monroe (5/10), and Ogle (5/10). Observations of leaf feeding and cutting have been reported from several areas of the state, including DeKalb, Effingham, Kankakee, and Monroe counties. These reports suggest that producers just about anywhere in the state should remain vigilant in their scouting efforts for potential black cutworm injury. Table 1 provides some projected cutting dates based upon previous intense captures and projected heat-unit accumulations.

Mike Gray, Extension Entomology, (217)333-6652

Table 1. Potential dates when 300 heat units above 50 degrees F have accumulated from an intense moth capture, indicating when black cutworm larvae are large enough (fourth instar) to cut corn seedlings.

Date of intense moth capture (9 or more moths caught over a 1- to 2-day period) County of intense moth captureProjected date when 300 heat units (base 50 degrees F) have accumulated from an intense capture
April 11ClarkMay 25
April 12MaconMay 25
April 16HancockMay 26
April 16VermilionMay 26
April 26PikeMay 24
April 28FordMay 28 or May 30
April 29AdamsMay 25
May 3ClarkMay 27 or May 30
May 6PikeMay 28
May 6WayneMay 28
May 7LaSalleJune 2 or 5
May 10OgleJune 6
May 11MonroeMay 30
May 14MaconJune 1
May 14HancockJune 3
May 15LoganJune 2

Note: Two dates may be listed for the same county if the heat-unit accumulations were generated from different Illinois Climate Network sites. Heat-unit projections were provided by Bob Scott, Illinois State Water Survey.