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Western Bean Cutworm Update

Posted: August 28, 2012

Western Bean Cutworm Monitoring Network is winding down with record numbers.
Fig. 1.  Western bean cutworm caterpillar found in Centre County in 2011

Fig. 1. Western bean cutworm caterpillar found in Centre County in 2011

Penn State Extension’s Western Bean Cutworm Monitoring Network is winding down after trapping moths continually since mid-June.  Unfortunately, this year we saw more moths than ever; the current count is at 1260 moths.  As a reminder, last year we caught a total of 350 moths statewide; so we have had in our pheromone traps.  Most of the moths this year were found in Potter and Erie counties and we have received a few reports of eggs being found in fields and larvae being found in corn fields.

Recall that western bean cutworm is an ear feeder and acts like corn earworm in that it feeds on the kernels; however, while only one or two corn earworms tends to infest ears, several western bean cutworm larvae can occur in each ear.  Please keep your eyes out of populations of western bean cutworm caterpillars in your fields.  We have yet to receive a report of economic damage from this pest species, so we are keen on hearing any reports from folks in the field.

Western bean cutworm caterpillars do not have any lines along the length of the body like corn earworms, and also have a broad “neck” with three distinct thin lines.  These features also distinguish them from sap beetle larvae, which can commonly be found this time of year and are small and white with darker head capsule.

Contact Information

John Tooker, PSU Entomology Specialist, jft11@psu.edu