Wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), Palaearctic in origin, is thought to have been introduced into North America in the early 1800s. It is a major pest of spring wheat (Triticum aestivum Linnaeus (Poaceae)), durum wheat (T. durum Desfontaines), triticale (X-Triticosecale), and, to a lesser extent, spring rye (Secale cereale Linnaeus (Poaceae)) throughout the northern Great Plains. Climate is the principal factor regulating the distribution and abundance of most insects. A bioclimate simulation model was developed to explain the current distribution and abundance of S. mosellana. The current distribution for North America, Europe, and Asia was consistent with model projections. General circulation model scenarios (CSIRO-MK 3.0 and MIROC-H) for the 2030 and 2070 time periods were applied to the bioclimate simulation model of S. mosellana to assess the potential impact of changing climates on their distribution and relative abundance. Potential changes to relative abundance and distribution were most sensitive to time period, as opposed to climate change scenario. Differences between the MIROC-H and CSIRO-MK 3.0 models were restricted to particular regions in North America. The study found that the range and abundance of S. mosellana, and associated crop risk, was predicted to expand in a northerly direction and contract across the present southern limits.