Fly Fishing Entomology 101 – Stoneflies

entomology 101 - stoneflies

The late Bud Lilly said he often fished a hole with a streamer and caught nothing. Then, he tied on a Rubber Legs nymph, went back through the same water, and caught a nice fish.There’s a reason for this: trout love Stoneflies! So you should too.

Here’s a brief profile of this species:

Names and Varieties

  • Stoneflies belong to the order “Plecoptera.” If you’re an entomologist who is into etymology (that is, a student of insects who is into the study of word origins), this Latin term comes from two Greek words: “braided” and “wing.” Yes, it looks like Stoneflies have braided wings!
  • The four most important Stonefly species for fly fishers (with apologies to the smaller Little Brown Stones and Olive Sallies) are Salmonflies, Golden Stones, Yellow Sallies, and Skwala.

The Basics

  • Stoneflies spend most of their lives in the nymphal stage that varies in length from seven months to four years. Yes, four years! That’s why Stonefly nymph patterns can work any time of the year. For example, Dave, my podcast partner, and I have had great success with them in late October on the Gardner River in Yellowstone National Park.
  • Stoneflies have an incomplete metamorphosis, existing in only two stages: nymph and adult. Mature nymphs migrate to the shoreline and then crawl out of the water. They emerge into the adult stage anywhere from a few inches to fifty feet from the river’s edge. Their emergence usually takes place at night—out of the sight of birds that would prey on them. The adult Stonefly emerges when its nymph skin splits. Then it slowly crawls out and walks away from the shuck.
  • Stonefly nymphs have long, segmented bodies with two antennae sticking out of their heads, two tails, and three pairs of legs. Each leg has a couple claws which enable Stoneflies to grip the rocks in the swift water they inhabit.
  • Adult Stoneflies mate in streamside vegetation rather than in the air. However, the egg-laden females then fly over the water—with their abdomens hanging down—to deposit their eggs (which then sink to the bottom of the river). Trout can go crazy when Salmonflies or Golden Stones are depositing their eggs. The other reason you might entice a trout to take a Stonefly pattern on the surface is the tendency for Stoneflies to fall into the water from vegetation. I’ve seen Salmonflies get blown by the wind into the Yellowstone River in June.
  • Smaller Stoneflies (Little Brown Stone, Olive Sally) range from ¼ to ½ inch in length. Yellow Sallies and Skawala can approach an inch. Golden Stones can reach 1 ½ inches, while Salmonflies can extend to 2 inches.

Effective Patterns for Stoneflies

  • You can’t go wrong with Stonefly nymphs year round! My favorites are the Rubber Legs patterns with either a black or brown body in a size 4 to 8. Aside from the obvious patterns (Golden Stone Nymph, Yellow Sally Nymph, etc.), try a Kaufman’s Golden Stone or a Kaufman’s Black Stone. A Copper John in a size 12-16 usually works as well as a Yellow Sally Nymph. Similarly, a Hare’s Ear will fill in quite nicely for a Golden Stone Nymph (in sizes 4-8) or for a Skwala Nymph (in sizes 10-12). Did I mention how effectively the Rubber Legs patterns work? Yes I did, but it’s worth repeating. When all else fails, put on a big nymph with rubber legs!
  • For Stonefly adults, I like a Yellow Stimulator or a Madam X (size 6-8) for imitating Golden Stones. An Elk Hair Caddis with a green abdomen (size 10-12) will work well for Olive Sallies. If you get a chance to fish the Yellowstone River in June (assuming the runoff hasn’t turned it brown), an Improved Sofa Pillow or Warren’s Salmonfly (size 4-8) will do the job.
  • The size and color of a particular Stonefly species will vary from one river to another. After all, Golden Stones come in four subspecies. Also, some rivers (like the Missouri in Montana) do not have many (if any) Stoneflies. So check with your local fly shop before you hit a particular river.

Other Entomology 101 Articles & Sources

    Fly Fishing Entomology 101: Blue-Winged Olives

    Fly Fishing Entomology 101: Caddisflies

    Fly Fishing Entomology 101: Pale Morning Dun

    Sources: Dave Hughes, Jim Schollmeyer, Bob Granger

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