Wheat stem sawfly, Cephus cinctus Norton, is an economically damaging pest of wheat in the Northern Great Plains and Canadian Prairies. Since wheat was first introduced over a century ago, C. cinctus has had a comparatively short time to evolve population differences in wheat, but may exist in distinct populations that have adapted from local native grass communities. In the laboratory we examined C. cinctus adult emergence from diapausing larvae collected in the spring from two locations in northern Montana. We controlled temperature and relative humidity in separate growth chambers. Adult emergence of C. cinctus from the Loring location was lower than from the Havre location at 15°C and 30°C, but no differences were evident at optimal temperatures of 20°C and 25°C. Diapausing larvae yielded a higher proportion of females from Havre than Loring across all conditions. Higher relative humidity improved adult emergence, and emergence was greatest from a hollow stem wheat variety (‘McNeal’) widely used by Montana farmers. Similar, but lesser emergence occurred from a less widely planted, resistant solid stem variety (‘Ernest’) and from another popular hollow stem variety (‘Reeder’). The Havre larval population may have yielded more females than from Loring because more female eggs were laid initially or female larval survivorship was greater, or both. Wheat stem sawfly post-diapause metamorphosis and subsequent adult emergence is influenced by sawfly population, temperature, relative humidity, and the wheat variety in which development occurs. This information is critical as we seek to model C. cinctus adult flight and oviposition periods.