University of Illinois

No. 11/June 6, 1997

Black Cutworm Moth Monitoring Program Concludes

Cooperators ended their survey efforts for black cutworm moths on May 31. Even though weekly reports of flight activity will conclude with this issue of the Bulletin, growers who planted very late will need to be alert for potential cutting for several weeks. Recall that cornfields remain susceptible to economic injury as long as plants are in the 4-leaf stage of development or below. For the week of May 24 to 31, moths were captured once again throughout the state. Volunteers in the following 19 counties reported moth captures: Adams, Boone, Bureau, Brown, Christian, Clark, Edwards, Ford (intense), Fulton, Hancock, Iroquois, LaSalle, Macoupin, McHenry (intense), Ogle, Piatt, Randolph, Richland, and Stephenson. Intense captures occurred in Ford County on May 27 and in McHenry County on May 24. Projected cutting dates are provided in Table 1.

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
May 7LaSalleJune 7 to June 9
May 10OgleJune 12
May 14MaconJune 6
May 14HancockJune 8
May 15LoganJune 7
May 22FordJune 12
May 24McHenryJune 14 to June 15
May 27FordJune 14 to June 15

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.

A few of our cooperators have called to let us know that on occasion their captures have not been reported in the Bulletin. This occurs when we don't receive moth-capture postcards before our publication deadline. Hopefully, projected cutting dates provided for nearby counties have been of some use to you in your scouting efforts this season. We are very thankful to all our cooperators who assisted with this program, and next year we may implement a slightly different reporting format.

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