Winter Survival of Western Bean Cutworm

by Bruce Clevenger, Defiance County
2010 brought a new observed level of the Western Bean Cutworm to NW Ohio corn production. Defiance and Fulton Counties each caught over 400 WBC moths in their respective four traps during summer monitoring and each county located at lease one field with WBC larves in the corn ear ( 2010 trap counts map of Ohio). However, 2010 corn fields did not reach economic thresholds that would warrant rescue treatments.

Since 2006, WBC has increased in numbers here in Ohio to the point where NW Ohio might expect the insect to complete its life cycle by over wintering rather than only moth flight migrating to Ohio during the growing season.

How do they survive the winter? Large larvae (6th or 7th instar) emerge from the ear and fall to the ground, burrow 3 to 6 inches into the soil, and construct an earthen overwintering cell (Figure). They spend the winter inside this cell in a pre-pupal stage. Larvae pupate in late May followed by adults crawling up through the soil with emergence starting in early July.

OSU Ext Factsheeet: http://ohioline.osu.edu/ent-fact/pdf/0040.pdf reference: http://tinyurl.com/37asbqe (Univ. of Nebraska, Lincoln)

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