fly fishing the baetis hatch in Montana

Baetis are a genus of mayfly that hatch in the spring and the fall. These small insects have olive-bodies and gray wings. They are frequently referred to as "blue winged olives", "BWOs" and "olives". There are multiple species baetis, but they all look similar to the non-entemologist. In Montana baetis hatch from March-May and from late Septmber-November. The hatch is often 20-50 times more prolific on cloudy, rainy, snowy days.

On sunny days, baetis are still very imortant. Dry fly fishing can be found in back eddies that concentrate cripples. The best fishing will be subsurface fishing nymphs. Pick your favorite top fly but hang a baetis nymph or emerger 18" as the trailer. Many people don't realize that emergers actually work great when below some split shot and fished deep. The baetis usually start emerging in the very late morning and continue until late in the afternoon. This coincides with the best fishing of a spring or late fall day, even if you are throwing streamers. The presence of the insects simply gets trout thinking food!

On cloudy days it is time to grab the dry fly rod and target rising trout. Rainbows will typically pod into groups...typically in size classes while browns will be solitary. Pay close attention to the rise forms...if fish are porpoising or you can see their backs, they are probably eating emergers or cripples just below the surface. If you see bubbles or fish snouts they are eating the duns on the surface that are drying their wings. A great strategy is to target both by fishing a small dry like a parachute, thorax or cripple dry on top with an emerger fished just 12" behind tied to the bend of the hook. CDC emergers are a great choice for the second fly...no need to grease them.