Issue No. 14, Article 2/July 9, 2010
Western Bean Cutworm Moth Captures Increase in Northern Illinois: Scouting Should Be Underway
Dale Baird, University of Illinois Extension crop systems educator, reported on July 6 that he found numerous western bean cutworm moths in a pheromone trap he monitors in Lee County. Dale said that this 2-day capture was the largest--49 moths--since he began monitoring for this pest five years ago. Extension entomologists Christian Krupke and John Obermeyer at Purdue University reported on July 2 that western bean cutworm moth captures were beginning to intensify and that egg hatch was underway in Indiana.
Fields most at risk, especially ones with sandy soils, include those in northern Illinois and Indiana. Scouting should begin in earnest; examine plants for egg masses on the upper surfaces of leaves on the higher portions of plants. Larvae that have hatched may be found in the whorl feeding on the tassel or leaf tissue. Cornfields that are just beginning to pollinate are very attractive to egg-laying moths. In determining the percentage of plants infested with eggs, it's a good idea to examine 20 consecutive plants in five different areas of a field. If 8% of the plants are infested with eggs and/or larvae in the whorl, a treatment should be considered. If a treatment is too late, larvae may have already moved into the ear through the ear tip, and effectiveness of any control measure would be significantly compromised. Transgenic Bt hybrids expressing the Cry 1F protein have proven effective against this insect. For more detailed information on the biology, life cycle, and management of the western bean cutworm, see ipm.illinois.edu/vegetables/insects/western_bean_cutworm.--Mike Gray