Surviving from the dawn of history the Diura stonefly group live in cool, clear, oxygenated water. In late spring the two species of Diura crawl as larvae from the river bed onto the band and shed their leather jackets.
The Stoneflies (Plecoptera) are primitive water insects, and smaller than the sedge fly which is deemed more important to the fisherman. The stonefly larvae serve as a water quality indicators since they cannot stand any pollution. In Finland there are about 30 different species of the stonefly, compared to 3000 found around the world, this because they only appear in cool, clear, oxygenated water usually rapid rivers, or stretches of stream with rocky or gravel bottoms. The type mostly found in Northern Finland.
Diura
To Perloididae family belongs two species of the Diura genus: Diura bicaudata and D. nanseni. They belong to the biggest stoneflies that appear in Finland (measured about 20 mm, 0,5"). The best season for the larvae to grow is winter. You can find them in May underside of the bank stones around rapid and stream stretches' of river waiting for the right moment to dash off to the bank and take off their winter "leather jackets".
It has been shown after years of research that the grayling consumes both stages of the stonefly; the larvae and the adult. In 1996 the grayling in one river was found only to have consumed the Diura larvae, we can conclude from this that it is a very important source of nutrition for the grayling.
Unlike the Taeniopteryx nebulosa, which appears in April or the Taeniopteryxes which start to hatch on the snowbanks of Oulu in Northern Finland, the Diura are late hatches only appearing in May and June.
The Diura hatches later than the stonefly more familiar to fishermen, Taeniopteryx nebulosa. In the latitudes of Oulu, the Finnish city, Taeniopteryxes start to hatch already in February.
When it comes to fishing, imitations of yellowish brown Diura larva work best in May and June. The darker adult is good in late June and in early July. In slower stretches of streams these flies have not been so effective. In swift rapids the situation is the opposite - graylings sometimes snap the fly so that the water splashes!
The variety of details or plain beauty?
I have been fishing with both complex and simple larva imitations and I have noticed that the latter ones fish better. In my later larva imitations I have paid attention to color of body, rib and simple wingcase, instead of details. The shape of the fly has formed during the tying.
In choosing the wing material for adult imitations I think mobility is the most important thing. Wings made of varnished feather or self-made wings out of silicone sheet haven't worked even half as good as duck CDC feathers. Fly bodies tied of hard and sleek material are similarly making way for furry dubbing bodies. On the other hand latex and bast have worked just about satisfyingly.
Fishing method: free swimming upstream and surfacem, in rapids, works also as sinking fly.
| Diura stonefly: CDC-Diura |
|
Model: adult imitation Developer: Pekka Väisänen Hook: Kamasan B800 # 10 Thread: yellow 8/0 - 12/0 Tail: olive green facehair of hare Abdomen: mixture of 3/5 soft fiber, shiny black chrystal thread, 1/5 Oliver Edwards Masterclass Antron nr 6, 1/5 SLF Finesse nr 10 (rusty yellow) Abdomen back: dark spirit dissolvable felt-tipped pen Rib: fluorescent green silk Wings: two CDC feathers on their side, top wing gray Z-Lon Thorax: 1/3, like abdomen Hackle: black Metz cock hackle as thorax hackle, same for abdomen when needed Antennas: like tail |
- Translation © Janne Väisänen 1999 -
The translator wishes to thank
Sandra Slaney for her help
with this article.