Issue No. 18, Article 5/July 25, 2008
Numbers of Western Bean Cutworm Adults Captured in Pheromone Traps
Numbers of western bean cutworm adults captured in some pheromone traps in Illinois recently increased noticeably. On July 22, Dave Feltes, University of Illinois Extension IPM educator, captured 176 moths in his trap near Morrison, a marked increase over his previous weeks' captures. A glance at the data submitted to Iowa State University's Western Bean Cutworm Monitoring Network reveals that triple-digit numbers of western bean cutworm adults have been captured in other traps recently, too. These numbers still pale in comparison with Iowa's past data, but the sudden upsurge bears watching.
In any corn that does not have the Herculex 1 Insect Protection trait, scouting for western bean cutworm eggs and larvae is strongly encouraged. Remember to look for eggs and larvae on the upper surfaces of leaves, from the ear to the tassel. The current threshold suggests that insecticide application may be warranted if 8% or more of the plants are infested with eggs and small larvae. Timely application before the caterpillars get into corn ears is essential for good control.--Kevin Steffey