Allocapnia illinoensis Frison 1935

Allocapnia illinoensis Frison, 1935 Notes This species is commonly known as the Illinois Snowfly (Stark et al. 2012). Isolated populations of this rare species have been reported mainly from eastern Canada, south to Virginia, and west to Illinois (Ross and Ricker 1971, DeWalt et al. 2024). Ross et al. (1967) discussed the post-glacial colonization of this species into eastern Canada. Ross and Ricker (1971) provided a distributional map of this species that included three localities in eastern New York State (their fig. 97) yet without precise locality information. Myers et al. (2011) provided the most recent reports of this species from a first order low gradient stream with a substrate composed primarily of sand and cobble, with moss covering some of the larger in-stream substrates. Harper and Harper (1983) reported that A. illinoensis “ dominate ” in small streams of southern Quebec. Webb (2002) presented evidence that this species has been extirpated from Illinois. In New York, adults of this species have been collected from early March through early April (Fig. 7) but infrequently from streams and rivers of moderate elevation 392-427 m asl (Fig. 9). This species is known from four unique locations in Level IV Ecoregions Eastern Adirondack Foothills (58 ac), Central Adirondacks (58 ad), Glaciated Low Allegheny Plateau (60 a), and Mohawk Valley (83 f) (Fig. 10 d).