Know Your Baetis
You’re at the Delayed Harvest, and you see the fish rising. You try every single dry in your box, but you still fail to catch a fish. You leave frustrated.
Here’s a hint: Know your Baetis.
Baetis mayflies are an extremely widespread genus. Several species are multi-brooded and may have two or more generations per season. There are at least five sub-species that hatch from Oregon streams and lakes. Hatches can occur nearly any time of year. This makes them common trout food and therefore very important to fly anglers. Baetis are found in both the western and eastern United States. The Latin name is the popular name used by the angling public. They are also commonly called blue-winged olives. However Baetis can also have tan or gray bellies. Trout can be very selective and prefer one shade over another. Most Baetis look gray on the water and can be quite deceptive. It pays to catch a hatched insect and examine it closely under magnification. Baetis are small, #16–20, but they hatch in big numbers. The best hatches occur on over-cast, rainy days. Hatches can start in late morning and extend into early after noon.
Baetis nymphs are swimmers. They inhabit many water types in streams, but prefer weedy riffles and runs. Use a “kick screen” in the morning. If you find Baetis nymphs with wing pads that are very dark, chances are there will be a hatch during that day. Nymphs will start getting restless in the morning. This is a good time to pound the bottom with Baetis Nymph patterns. Nymphs start drifting down the river and swimming to the surface in the late morning. Some nymphs might make several attempts to reach the surface before they actually make it. These insects are very small and don’t provide much food value unless they can be taken easily in a large quantity. The best places to fish are where riffles with small graveled weedy runs enter slow pools or slow back-eddies. The nymphs leave the bottom of the riffle and drive along the bottom for a distance. Then they attempt to swim to the surface while the water velocity slows down. When the nymphs reach the surface of the water, their wing pads break through the meniscus. They can hang there for several minutes as floating nymphs. As the skin splits down the back of the head and between the wing pads the dun starts to emerge through this tear. At this point the insect can neither swim nor fly. It is completely helpless and a perfect target for trout. The hatching duns can collect in quieter flows in very large numbers.
The trout know where these conditions regularly occur and also collect in large numbers. Feeding is usually slow and quiet. Look for snouts and fin tips. Target individual fish with pin-point casting.
To top it off, here is a video for the Baetis Dry Fly.
Ladies and gentlemen, Davie McPhail.
Tying a Sparse CDC Dun