The Stonefly
"The stonefly has always been my favourite bug for reasons I can't even begin to psycho-analyze. Perhaps it's their size or terrible appearance: veritable Quazimodos of streamside bell towers!"
Stoneflies: 
Order : Plecoptera from the Greek plekos meaning 'twined' or 'woven' and ptera means 'wing', which is evident from the adult stoneflies' pteras.
The stonefly has always been my favourite bug for reasons I can't even begin to psycho-analyze. Perhaps it's the size or their terrible appearance. Veritable Quazimodos of streamside bell towers, hiding by day in the crevasses of rocks and logs only to crawl out under the cover of night to shed their baleful exoskeleton and emerge into something that is…well… still big and still ugly.
I have to be honest, even adult stoneflies are less than attractive. They look the same as the nymph except they have these four large cross hatched wings folded over their bodies. You would think that if an insect goes to the trouble of metamorphing, they would emerge looking more like a butterfly then a monster. What also compounds their unfortunate lot is their clumsiness. As you watch them take flight, they seem to trip over themselves and tumble across the water in a graceless, uncoordinated flight to death.
I suppose I like stoneflies because they are big, ugly, and uncoordinated. It's like watching the Hunchback of Notre Dame. The way I view Quasimodo, is the same way I see the stonefly. First you feel revulsion, then pity, and finally, a genuine fondness develops for the misunderstood, and ultimately doomed giant.
Life cycle:
Nymph : Eggs hatch into nymphs on the bottom of well-oxygenated streams or rivers. The nymphal stage can last up to three years, where a nymph will moult over and over again until it develops completely. They feed on organic and vegetable matter and some species are carnivorous and will feed on mayfly nymphs and other insects. Stoneflies skip the pupal stage of the life cycle and go right to the emerging adult. This is known as an incomplete metamorphosis.
Nymphs will eventually crawl out onto a stone, tree branch, or log and remain until dry
Adult : When the nymph has dried sufficiently, the case will split and out comes the adult l
ooking the same as the nymph except with two pair of wings attached. Once emergence is complete the stonefly will fly off to nearby trees to mate. Males attract the females by drumming their abdomens on the tree branch, just to let the females know where they are. Then, once the females hear the primal beat, they presumably whisk their way to the waiting wings of the males. This all seems way too easy, no dramatic courtship ritual, no bobbing and weaving through the air chasing down a mate like the mayfly. I suppose it's nature's way of levelling the playing field. Cursed with a hideous appearance, Mother Nature generously ensures that it's easy for the male stonefly to get laid.
Once the coupling is complete, the female stonefly will then fly off and skim the surface of the stream, dipping their abdomens in the water and releasing their eggs. Some will actually crawl back into the stream and release their eggs on bottom structure. Depending on the species, stonefly adults may live for a couple of days to several weeks.
Fly Fishing Stones
The size of a stonefly nymph varies from 5 mm to 50 mm in length. One of the largest species of stonefly is the Salmon fly , Pteronarcys californica, ( ptero-narkaw meaning stiff winged). These large salmon flies can be found on rivers and streams. In the Kootenays, the nymphs are prevalent on the Columbia River and its tributaries, and act as a food source for trout all year round. 
During the winter and early spring I use a full sink line and dredge the bottom with a stonefly nymph, or a stimulator pattern tied onto a 3-4 foot leader. The stimulator works great as the deer hair keeps the fly suspended just off the bottom thereby avoiding snags. Cast into a back eddy or let the current take it out, then retrieve it very slowly to imitate a crawling stonefly. Like steel heading, the slightest pause in your line may be a strike so set the hook, and worry about a snag later.
Mid-April is when the Salmon Fly hatch occurs in earnest on the Columbia and when dry-fly fishermen drop everything and head to the river. A #2-6 adult Salmon Fly pattern or an Orange Stimulator works well. Imitate the splashing and fluttering of the female stonefly on the surface and get ready. The strikes will be fierce, as four and five pound rainbow rise to these piscatorial delicacies.
The brief Salmon Fly hatch of April is my favourite time of year to fish the Columbia River. It can last only a few days or a few weeks depending on the weather and river. I wait impatiently. As early as March I am streamside turning over rocks seeing their odious nymphal forms scurry for cover. Then, one day I arrive and see a multitude of empty husks still clinging to a branch. I look over the stream and catch the orange flicker of a clumsy Salmon Fly tripping over the water - I smile and think – big fly – big trout. Perhaps, this is really why my favourite fly is the stonefly.