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Stonefly
By Dick Babine
Plecoptera
| Phylum: | Arthropoda (460 Species Known) |
| Class: | Insecta |
| Order: | Plecoptera |
| Family: | Perlidoe |
| Genus: | Aeroneuria and Pteronoreys |
March's creature of the month is the stonefly. The Stone Fly is an important trout and salmon insect with which the fly fisher should be concerned. It is less important than the Mayfly or the Caddisfly, but anglers should be familiar with this insect and carry several dry and nymphal imitations, which resemble the genus Plecoptera, which means in Latin: pleco-"folded" and ptera- "wings."
Like the Mayfly, the Stonefly has an incomplete life cycle, by not going through a pupal stage. Only the nymph and adult stages are of importance to the fly angler. However, since the Stonefly emerges while the Caddisfly adult is still in command, little attention is given to the Stonefly nymph over much of the state, again because of the lack of knowledge concerning its use and the proper technique required for consistently being successful in luring strikes. This insect will make its appearance no later than late June and will last until around the end of July. Stonefly Nymphs require highly oxygenated water that has a medium to fast movement. The other requirement is that the bottom of the river or streambed be consisting of small-to-large rock aggregate. The name Stonefly probably came from where they are found along streams hiding or crawling in and around the rocks and stones.
Stoneflies, a relatively small group of aquatic insects but do represent the most colorful in nature. Golden Stones, Salmon Stones and the Nasqually Stone represent the largest species. Stoneflies have four wings, which are heavily veined. Lying flat over the body until the insect takes flight. Colors will range from bright yellow, misty gray, salmon pink, tan, brown and black.
These stones come off the water in morning to midday and in general are 6-8 mm in size. During the early spring emergence, they are often referred to as "Snowflies," and are observed crawling on the snow banks next to their home waters. This activity can occur in early March and continue through May. When this insect hatches, the larvae will crawl out of the water and hatch on land. The evidence of this activity is found along the riverbanks in the form of hundreds and hundreds of empty shucks, attached to rocks, tree trunks, shoreline bushes and any aquatic plant that reaches out from the water. When and more importantly if you observe this behavior, you know that the fishing later on just before sunset will be well worth the trip. The female will return at night to deposit the eggs into the water. Most females will skim the waters surface to dislodge the eggs from the female's abdomen. Others will actually crawl to the bottom of the stream and then release their eggs on submerged objects. The males sometimes emerge before the females, and some species actually attract females by beating their abdomen against a hard surface. A responsive female will often return the same signal. Stoneflies unlike the mayfly live as adults from a few days to around a month or more. These insects have very poor flight characteristics and therefore create quite a splashing and fluttering upon the waters surface during egg laying and for that reason attract the attention of hungry fish.
The real important thing to realize is that this aquatic insects life cycle is in some species more than 24 mos. And for that reason, this fly can be used almost year round. The real reason that this fly is useful is that in the early spring and late fall, when the Mayflies and Caddisflies have completed their life cycles, guess what's still around? So, in short, you can use the Stonefly nymph along with your Bucktails and Streamers for either the early or late season outings.
Nymphs: ½" to 1 ½" in length with 2 long antennae. 3 pairs of crab-like legs with terminal tarsi with 2 tarsal claws. This nymph will also have 2 medium length tails (cerci). These insects will have 2 separate pairs of wing pads. Unlike the mayflies one set of wing pads
Adults: adult stoneflies look much the same as the nymphs with the difference being that the wings are folded flat over the back and extend beyond the abdomen. At the end of the abdomen, the insect has 2 short tails.
Food: The nymphs will feed on decaying organic and aquatic vegetable matter. Some species are predatory feeding on other available aquatic insect life forms.
Habitat: Stonefly nymphs require well oxygenated water so are consequently found in rivers and streams amongst the rocks and bottom debris which make up the substrate in most riffled areas.
| Scientific Name: | Capniidae |
| Species: | Allocapnia |
| Common Name: | Little Black Stone |
These are the Snowflies that emerge in early spring and are sized 10mm (#18-#20.) They are short winged and black in color. This species will start emergence activities in early March and continue well into May.
| Scientific Name: | Nemouridae |
| Species: | Zapada |
| Common Name: | Small Brown Stone |
This is also a spring emerger but will appear shortly after the Tiny Blacks and also emerge until the last weeks of May. Use sizes #16 to #20
| Scientific Name: | Taeniopterygidae |
| Species: | Taeniopteryx |
| Common Name: | Brown Stone |
These are also winter into spring emerging stones and are a darker brown almost black.
| Scientific Name: | Perlidae |
| Species: | Acroneuria |
| Common Name: | Large Brown Stone |
These are your larger summer-emerging stoneflies. It is best to use a reddish-brown imitation and in sizes #8-#10.
| Scientific Name: | Pteronarcyidae |
| Species: | Pteronarcys |
| Common Name: | Salmon Fly |
This is the largest eastern stone and relished by all fly anglers. The fish will not hesitate to get a chance to bit into a good imitation of this insect. You will need hook sizes #8 - #12
Fishing Tips:
Stonefly nymphs are available to fish year round. These nymphs are very poor swimmers and prefer to crawl along the rocks and bottom debris, using their clawed crab-like legs. They eat small invertebrate animals, decaying plant material, organic matter, algae and bacteria. Some are predators and will eat anything smaller than themselves. They can molt their exoskeleton up to 30 times and some species take up to 4 years to develop from egg to adult. The adults look exactly like the nymphs except that they have folded flat wings over their back when at rest. Quite often they will loose their footing and end up helplessly drifting along with the down-stream current, attracting the attention of the fish.
Remember that fish will often target stones as they migrate towards the edges of the streams and rivers to crawl out of the water during emergence. These large tasty morsels will become very active before the Baetis start acting up, so take advantage of the situation.
In either case the Fly Angler must imitate this action by keeping the fly near the bottom, this can be achieved by casting up-stream or up and across and letting the fly sink and tumble with the current along the stream-bottom next to the bankings for maximum effect. Early on, fish a black or reddish-brown nymph, un-weighted, in a size 16-18 swinging it from mid-stream to the bank wet fly style.
Also the female laying eggs will attract fish because of her clumsily making contact with the water in an attempt to deposit the eggs. This is the very time the Dry fly approach is called for: imitating the fluttering, splashing movements of a female stonefly on the water surface will often provoke a violent response from fish.
A tying tip is that Elk Hair Caddis tied in black to reddish-brown will imitate the little Black, Brown, and Rust colored Stones.
If you're into using droppers, try a stonefly nymph behind an egg pattern. The egg will attract the fish but you will br surprised how many reject the egg and go after the nymph.
On your weighted nymph, add the weight 4 to 5 inches above the imitation. This allows the fly to move more naturally and tumble freely in the current.
