A 2-year field study was carried out to determine densities and stage-specific survival of eggs, second- and third-instar larvae, prepupae, pupae, and adults of Strobilomyia appalachensis Michelsen in a black spruce, Picea mariana (Mill.) B.S.P. (Pinaceae), seed orchard located in New Brunswick, Canada. Trends in stage-specific survival were similar for both years. Most individuals died during the second-instar stage, we suspect mostly because of failure to establish. The lowest stage survival occurred during the prepupal and pupal stages, due primarily to predation by ground-dwelling invertebrates.