Western Stoneflies
Early Winter Stonefly
Early Winter Stoneflies (Nemouridae, Capniidae, and Leuctridae families) are small black stoneflies (6-8mm) that emerge from January through March. They thrive in small streams with abundant coarse rubble and are often seen crawling on top of the snow along the river’s edge. Winter stones rarely produce dry-fly fishing, but a sparse black Pheasant Tail (#16-18) fished in the soft holding spots along the shore is often effective in late winter and early spring.
Skwalas
Skwala stoneflies (Skwala species) inhabit waters across the Rockies, from Alberta south through Colorado, as well as in Washington, Oregon, California, and Idaho.
The nymphs are 17 to 21mm long at maturity and have olive to dark brown bodies that are lighter-
colored on the bottom. Pat’s Rubber Legs (olive/brown), #8-10 Mercer’s Skwala Stones, and #8-10 Halfbacks are recommended nymph patterns.
The adults hatch from the last week of February through late April, typically peaking between the last week of March and the third week of April. Adult Skwalas are about the same length as the nymphs, with olive to dark brown bodies and mottled orange highlights around the legs and underbellies. Stranahan’s Bitterroot Olive Stoneflies, olive Foamulators, and pearl Crystal Stimulators (#8-10) make good adult imitations.
Salmonflies
Pteronarcys species, commonly called willow flies or Salmonflies, hatch from the first week of June through early July, depending on altitude, latitude, and water temperature. The nymphs (38-43mm) are dark brown or black and typically have rounder abdomens and shorter tails than other stonefly species. Adult Salmonflies have a wingspan of 2½ inches and brilliant reddish-
orange undersides.
Salmonfly hatches are famous for providing some of the best dry-fly fishing of the summer, with the hatch on most rivers progressing slightly upriver each day. Good timing is critical for success. During heavy emergences, the streambanks are littered with egg-laying adults and eager trout lined along the banks waiting for them.
Things can go wrong though, including inclement weather, spring runoff, and erratic flows.
You may arrive too early—before the hatch really gets going—or you may get there slightly too late and find the trout are crammed full of adults and they’ll decline your offering no matter how good your fly looks or how many fluttering adults are present. Though this rarely happens with hatches of mayflies or smaller stoneflies, during Salmonfly hatches trout do get full and slow their feeding. In this case, try moving several miles upstream or ahead of the hatch, where the trout are hungrier.
If you are early and the hatch isn’t happening yet, try dead-drifting nymphs along the shoreline where the naturals are gathered prior to emergence.
Effective nymph imitations include #6-10 Kaufmann’s Stones, Halfbacks, Dorsey’s Paper Tigers, ***** Creek Nymphs, and Pat’s Rubber Legs (brown/black). My favorite drys include #4-8 Sofa Pillows, Rogue Foam Stoneflies, Fluttering Stoneflies, orange Stimulators, and orange Foamulators.
Goldens
Golden Stoneflies (Perlidae family) begin hatching about two weeks later than Salmonflies in most watersheds, emerging between early July and mid-August. This means that on many rivers, adult Salmonflies and Golden Stones crawl the streambanks together for a period of time. However, Golden Stones are the most abundant of all large stonefly species in the West, and the hatch duration is much longer. On some waters, Golden Stones hatch for up to 30 days, or more.
Golden Stones thrive in both unregulated freestone streams and in tailwaters below deep bottom-release dams, so they are more common on more waters than the bigger
Salmonflies. Salmonflies rarely thrive in overly fertile tailwater fisheries or in spring creeks.
Golden Stoneflies are roughly the same size as Skwalas (17-23 mm). The nymphs are a speckled yellow brown, and the adults range in color from a rich golden brown to dark brown, with lighter tones around the legs and on the underbelly. They could be easily confused with Skwalas if it weren’t for hatch timing. Skwalas are early spring stoneflies, while Golden Stones are summer species, most prevalent in the month following the Fourth of July.
Golden Stonefly nymphs are important foods for trout on most Western watersheds through the entire year. In the weeks preceding the hatch, focus your efforts on the fast, rocky holding water near the banks. Barr’s Tungstones, Barr’s Tung Teasers, Pat’s Rubber Legs (brown/orange), Beadhead Hare’s-ear Nymphs, and Mercer’s Golden Biot Stones (#8-10) are a few of my favorite Golden Stonefly nymph imitations.
The best dry-fly fishing occurs in the afternoon, when the adults come back to the water to deposit their eggs. The trout key on these egg-
laying flights, and anglers can generally catch fish on the surface throughout the course of the day. Yellow and olive Stimulators, Rogue Foam Stoneflies (golden), and Amy’s Ants (olive) in #8-10 are excellent imposters.
Copyright © 2012 Intermedia Outdoors
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