Western Bean Cutworm: New Corn Pest in NY
By: Mike Stanyard

Well, it is official. The Western Bean Cutworm (WBC) has arrived in NY. At the 2008 Corn Congresses I gave a presentation on WBC as a potential pest of corn in the northeast. At that time, its eastwardly spread had been limited to western OH and southern MI. In two seasons it has made its way into WNY.

Path of Migration
The WBC has been a recognized pest in Colorado, Nebraska, and Kansas since the late 50’s. However, starting in 2000, WBC populations really started to blossom in Iowa and move across the whole state. In 2004, this pest was first found damaging corn in NW Illinois and by 2006 it had moved across WI, IL, IN and into MI and western Ohio. The adult moths are obviously good fliers and moved rapidly eastward.

First Moth Discovery in NY
Art Graves of Mycogen along with WNY Crop Management Assoc. placed pheromone traps for WBC throughout WNY this summer. The first adult moth was caught on July 21 and official species confirmation was made by Cornell University. Additional moths were caught in Livingston (2), Genesee (4), and Wyoming (5) Counties.

WBC moths were also caught for the first time in eastern Ontario, southern Quebec and Pennsylvania. The largest trap catch was 63 total moths caught by Penn State on our western border in Erie, PA.

Biology
Female moths lay their eggs on the upper third of the corn plant on the top side of the leaves. Eggs are white and usually laid in clumps of 50. The young larvae are dark brown with faint cross hatched markings on their back. Larvae feed on pollen in the developing tassel within the flag leaf and on silk in the ear. Larvae feed for about 35 days and develop through five stages (instars) on the plant.

Third instar and older larvae can be found feeding primarily on the ear tip. WBC can be easily be identified and differentiated from other similar feeding caterpillars (earworms & armyworms) by characteristic dark brown bands immediately behind the head (see photo).

Will WBC Overwinter in NY?
It was unsure if WBC would successfully lay eggs and produce larvae in 2009. On September 4, I received an email from Nate Herendeen saying he thought he found a WBC larva in a field in Lockport over in Niagara County. Upon seeing the beast, I confirmed his identification. So we know that WBC eggs successfully hatched and larvae made it to maturity. We will have to wait until next summer to see if it overwintered successfully.

At Corn Congress on January 13 and 14, I will review this new pest in detail, plans for monitoring and what we should be looking for in our corn in 2010.
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