Pictured: Western bean cutworm larva. Photo by K. Hamilton, DATCP.
The 2023 western bean cutworm moth flight currently underway is the largest on record for Wisconsin. It’s the highest in the 19-year history of western bean cutworm monitoring in the state, according to DATCP’s latest field report.
DATCP’s monitoring network of 42 pheromone traps has captured a cumulative total of 8,854 moths, or an average of 211 moths per trap since the survey began in mid-June. This preliminary count far surpasses the previous record of 4,804 moths in 36 traps — 133 moths per trap — collected last season.
Moths are still appearing in moderate numbers in survey traps, but counts across southern sites have decreased markedly since the flight peaked July 21-27. Most of DATCP’s 42 monitoring locations reported lower counts this week, the exceptions being sites in central and far northern Wisconsin and one anomalous Green Lake County trap that captured 270 moths.
The network’s total weekly capture of 1,098 moths is a sharp decline from 2,674 moths last week and 3,431 moths the week before.
DATCP expects this season’s large flight to produce localized heavy larval populations in the central areas of the state with a history of higher western bean cutworm pressure. Early-stage larvae have been observed in the last few days during surveys in Adams, Juneau, Monroe, and Trempealeau counties.