During the grasshopper egg surveys conducted in Saskatchewan by the Dominion Entomological Laboratory at Saskatoon since 1932, bee fly larvae were commonly found destroying grasshopper egg pods. In the early years of these annual surveys little was known regarding the species, life-history or economic importance of these larvae. This prompted a study of the bionomics of the species, subsequently determined as Systoechus vulgaris Loew, and a morphological study of its immature stages.