Western bean cutworm flight and egg masses increasing

Recent lower temperatures may cause western bean cutworm egglaying to increase, especially in corn fields.

There are about 70 traps in the western bean cutworm network in 23 Michigan counties. Traps in Branch/Hillsdale counties picked up a moderate flight last week (tens of moths). This week, moth numbers in Montcalm County increased (100-plus in some traps) and we found a few egg masses. With the lower temperatures, egglaying should pick up, especially in areas that got some rain on Friday (July 19, 2013).

The variability in corn development, both within a field and from field-to-field, will benefit western bean cutworms. Females are great at finding pre-tassel corn, and this year they will be able to find attractive egglaying sites for many weeks. I am not sure if or how this will impact infestation of dry beans. Perhaps western bean cutworms will spend more time and lay more eggs in corn fields versus beans. On the other hand, late-planted dry beans may still be very attractive to moths and, depending on flight levels, whose fields may still need to be treated.

Dr. DiFonzo’s work is funded in part by MSU‘s AgBioResearch.

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