Net-winged midges (Diptera : Blephariceridae): A food resource for brook trout in montane streams

We report on the importance of net-winged midges (Diptera: Blephariceridae) in the diet of three native populations of brook trout, Salvelinus fontina lis (Mitchill). One population, studied mostly during 1992 and 1993, was fr om the Rapidan River; Shenandoah National Park, Virginia. The other populat ions, studied in 1993 and 1993, were from Trail Creek and North Fork Rock C reek, both subalpine streams in Medicine Bow National Forest, Snowy Mountai ns, Wyoming. Rapidan River samples contained 411 larvae and adults, mostly of Blepharicera appalachiae Hogue & Georgian, recovered from 121 trout. Dur ing the study period, there were marked shifts in the relative consumption of larvae to adult BI. appalachiae, then to Bl. similans Johannsen. These s hirts presumably renflect temporal patterns of blepharicerid activity and p cr haps changes in trout predatory behavior (benthic to surface feeding). A r Wyoming streams, fourth-instar larvae and adults of the net-winged midge, Agathon elegantulus von Roder, were recovered from 34 trout. Relative to t he Rapidan population. western trout populations consumed lower numbers of blepharicerids. Because net-winged midges are moderately large Airs that ca n be seasonally abundant in many streams, we posit that blepharicerids can he a significant component of trout diets.