Blue Winged Olives are typically the first significant emergence of the year throughout Montana. From the glassy flats on the Bighorn, to the big back eddies on the Yellowstone, to the large pods of feeding fish on the Clark Fork River trout certainly key in on the various stages of this relatively small Mayfly.
Unlike other Mayflies, Baetis produce several broods throughout the year, with the first being in the spring between March and May. The most significant factor affecting this emergence is water temperature. The magic temperature seems to be in the low 40’s right around 43 degrees. BWO emergences typically take place in the early afternoon when water temperatures have had a chance to warm up a few degrees triggering the hatch. Having your stream thermometer handy at this time can prove invaluable.
While we all enjoy fishing to rising trout on the surface, trout key in this mayfly long before you see them rising on the surface. The nymph and emerger stage of the Baetis life cycle can offer tremendous action to the angler. When optimal conditions exist Baetis will exist in a river in large quatities and the trout know that they are there. Nymphs dead drifted near the bottom are always effective. Once the water begins to warm the nymphs will begin to emerge to the surface. Classified as swimmers, Baetis nymphs emerge rapidly to the surface and are easily identified by the fish. Stopping your drift and allowing your flies to rise to the surface can produce viscious strikes. Also right before your drift is about to drag out, give your flies a few slow but deliberate strips to induce a strike. On countless occasions I have had clients begin to stip their line in to recast and a fish takes their fly.
Once the mayflies are hatching in the surface film or drifting on the surface as duns, fishing with a dry line becomes the preffered method of fishing. Duns on the surface can range in size from 16 – 24 throughout the year, with the duns typically being the largest in the spring. While a good presentation and accurate drift are required, fish are typically not that selective when it comes to BWO fishing in the spring. Large pods and all out frenzies allow the angler to approach relatively close and the trout seem to be left with their guard down during the climax of the emergence.
For those of you who haven’t experienced early season Blue Winged Olive fishing on a river such as the Bighorn it can be nothing short of spectacular. Early season, pre-runoff fishing in Montana is often very overlooked by the traveling angler and solitude can be found on many rivers. The timeing of the yearly emergence on certain rivers can be very dependable. Rivers that I have found them to be best on our the Bighorn, Beaverhead, Missouri, Clark Fork and Madison Rivers.
This post was written by Bighornangler