Occurrence of Sitodiplosis mosellana (Diptera: Cecidomyiidae) and its parasitoid, Macroglenes penetrans (Hymenoptera: Platygasteridae), in northeastern Montana.
The wheat midge, Sitodiplosis mosellana (Géhin), is an infrequent but devastating pest that has been present in western North America for at least 100 years. This note provides the first published report of the presence of the wheat midge and its parasitoid, Macroglenes penetrans (Kirby), in Montana. Annual surveys were conducted in Daniels, Roosevelt, Sheridan, and Valley counties of northeastern Montana for 5 years (2000-2004) using a systematic soil sampling method to collect overwintering wheat midge larvae. In addition, in 2004, infested wheat heads were collected from 10 fields in Sheridan County, and wheat midges and parasitoids were reared. The wheat midge occurred in all four counties, though at relatively low levels. Densities fluctuated across years and locations, with the highest densities (>200 midge larvae/m2) occurring in Sheridan and Roosevelt counties. Macroglenes penetrans was found at all 10 sample sites and constituted up to 52% of the emerged adults (midges+parasitoids).