Central ND News

Soil samples from North Dakota wheat fields indicate a significant decrease in overwintering wheat midge larvae, according to Janet Knodel, an entomologist at North Dakota State University Extension. "For the fifth year in a row, low populations of wheat midge were present, potentially reducing farmer's inputs for wheat midge management," Knodel said. However, she warned that "wheat midge can still increase in pockets where timely spring rains occur in 2025."

From August to October 2024, NDSU Extension agents collected 1,920 soil core samples from 192 fields across 21 counties. The survey revealed positive results for wheat midge at only three sites—Towner, Pierce, and Ward counties—each showing low cocoon levels (1-200 cocoons per square meter), which are unlikely to impact yield.

Knodel noted the consistent low presence of wheat midge over recent years: "The majority of the soil samples had zero wheat midge cocoons for the past five years." She attributed this trend to drought conditions that disrupt the synchronization between pest emergence and crop vulnerability stages.

Despite these findings, Knodel advised farmers to remain vigilant: "With very low populations of wheat midge for the fifth year in a row, scouting will be most important in continuous wheat fields." Environmental conditions such as spring rains could still favor larval development and adult emergence.

In addition to soil sampling, pheromone traps have been used as an early warning system. In 2024, 20 traps across 18 counties captured fewer adult midges than previous years. Despite this decline, trapping indicated that the pest remains widespread. Beneficial parasitoid wasps that prey on wheat midge have also declined alongside their host.

Knodel emphasized that monitoring efforts continue to guide integrated pest management practices: “Pheromone traps are used as an 'early warning' system... If more than 10 midges per trap are observed then field scouting should be initiated.” The data shows a notable drop in both pests and beneficial wasps compared to earlier years.

Overall, both soil sampling and pheromone trapping indicate a significant reduction in wheat midge populations over recent years; however, continued vigilance is recommended due to potential environmental changes affecting future infestations.