Western Bean Cutworms No Longer 'Western'

WBCWs popped up all over Pennsylvania and New York this year, warns entomologist.

Published on: Oct 8, 2010
Western bean cutworm got their start in the western Corn Belt, where they dined on dry beans and sporadically on corn. By year 2000, they'd taken a slow train eastward, reaching Ohio in 2006.

In 2008, cutworm moth traps put out by Penn State Cooperative Extension picked up 100 moths in Erie County, says Extension Entomologist John Tooker. "This year, we found close to 400 of them all over the state. And they've moved into New York, as well."

If the WBCWs follow their usual expansion plan, local counts will be substantially higher in 2011. Corn growers should begin scouting and preparing for them, adds Tooker.

Western bean cutworm completes a single generation per year. Adult moths fly in mid-summer and females lay eggs on the upper surfaces of corn leaves. As a late-season corn pest, WBC larvae feed on tassels, silks, and developing kernels and can cause severe damage.

BUG WATCHER: Penn State Entomologist John Tooker advises corn growers to learn what the western bean cutworm moth looks like, perhaps put out pheromone traps in 2011 and prepare for them
BUG WATCHER: Penn State Entomologist John Tooker advises corn growers to learn what the western bean cutworm moth looks like, perhaps put out pheromone traps in 2011 and prepare for them

Chemical control can be a challenge because larvae spend considerable time inside the husk.  Some transgenic corn varieties have activity against western bean cutworm caterpillars.

The easiest way to monitor the presence of this pest is trapping of the adult moths. In 2006, three adults were caught, six in 2007, 150 in 2008 and over 500 in 2009. Most moths have been caught in the extreme northwest or west central portion of Ohio.

The adults emerge in late June-early July after

For more details and pictures, go to: ento.psu.edu/extension/field-crops/corn/western-bean-cutworm.