First captures of black cutworm moths have been reported from "top to bottom" throughout the state of Illinois. Ron Hines, senior research specialist at the Dixon Springs Agricultural Center in Pope County, reported an intense capture of black cutworm moths during the evenings of April 3 and 4. As Kevin Steffey indicated in issue no. 2 of the Bulletin, we consider an intense capture of moths to equal nine or more moths caught over a 1- to 2-day period, using pheromone traps (sticky-wing traps). Following an intense capture, Bob Scott, Illinois State Water Survey, can offer predictions regarding when cutting of corn plants may begin to occur. Based on historical temperature records, Bob Scott indicates that cutting may begin to occur in southern Illinois cornfields near Pope County as early as April 26. This is based on a predicted accumulation of 300 heat units (base 50°F), following an intense capture of moths. In central Illinois an intense capture of moths was reported by Doug Gucker, Piatt County Extension Unit, near the community of Cisco. On April 7, Doug found six moths in his pheromone trap, and on April 8, three black cutworm moths were found. Jeff Hoffman, Piatt County FS, also reported numerous moths in his traps during this same time frame. We will provide projected cutting dates for central Illinois in an upcoming issue of the Bulletin. Jim Morrison, crop systems Extension educator, Rockford Extension Center, also reported his first captures of black cutworm moths for the season. On April 10, Jim found two moths in his pheromone trap located in Winnebago County. So, black cutworm moths have made their annual spring migration throughout Illinois.|
As soon as corn gets planted and begins to emerge in southern Illinois, cutting injury caused by black cutworm larvae could be evident. Be on the alert for pinholes in the leaves as soon as the seedlings emerge. Although pinhole injury is not economic, it suggests that small cutworm larvae are present and could cause economic cutting injury as soon as the larvae are large enough. As a general rule, rescue insecticide applications may be warranted when 3 to 5% of 2- to 4-leaf stage seedling corn plants are being cut below ground. Some seed-production managers begin to trigger insecticide rescue treatments when 1% of the plants have pinhole injury, assuming that this early injury may result later in economic cutting. We will continue to provide updates throughout the spring regarding the status of this sporadic pest.--Mike Gray and Kevin Steffey
Checking black cutworm moth captures in pheromone trap.
Black cutworm moth (note black "dagger" on forewings).
Pinhole feeding on seedling corn plant by black cutworm.