The western bean cutworm moth flight, which has been ongoing since mid-June, is shaping up to be one of the most significant in Wisconsin’s history. The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) has reported that its network of 69 pheromone traps has captured a staggering total of 14,654 moths to date. This translates to an average of 212 moths per trap since the emergence began eight weeks ago. This makes it the second-largest flight on record in the state.
This year’s numbers are rapidly approaching the all-time record set last season, which saw 9,351 moths captured in 42 traps. The current season’s count is the second highest in the 20-year history of western bean cutworm monitoring in Wisconsin.
While moths continue to appear in high numbers in northern survey traps, counts across southern sites have decreased significantly since the flight peaked between July 19-25. The majority of DATCP’s 69 monitoring locations reported lower counts this week, with the notable exception of northeastern Wisconsin. One trap in Marinette County recorded an anomalous capture of 1,095 moths, contributing to the network’s total weekly capture of 2,678 moths. This is down sharply from 4,765 moths last week and 3,658 moths the week before.
As observed in 2023, this season’s substantial moth emergence is expected to result in localized heavy larval populations in the central and southern areas of the state. The survey map also shows an unusual expansion of high trap counts in the northwestern and northeastern regions. This uncharacteristic pattern may be attributed to the low overwintering mortality rates during the mild 2023-2024 winter.
