Baetis / Blue-Winged Olive

Life Cycle = egg, larva, sub-imago, adult
Baetis Nymph
More pictures coming...

Size/Profile Larva (nymph):  6 - 15 mm (flat tapered body with distinct wing case and long split tail))
Adult/Sub-Imago:  6 - 15 mm (tapered body with two large gray wings standing upright with a slight tilt back and a long split tail)

Note: tails are typically as long as the body.

Colors Larva (nymph): top is olive/brown or dark brown, bottom is cream, wing case is typically black.
Adult/Sub-Imago: top is light olive, dark olive, or olive/gray, bottom is light olive.  Wing is gray.
Action Larva: crawl on the bottom but swim frantically when rising to the surface to emerge.
Adult: Most of the time very still on the surface of the water as the wings dry.  Females skim water and dip occasionally to deposit eggs.
Habitat Baetis are often found in faster moving water where more oxygen is present.  They breathe through gills on their abdomen and eat aquatic plants.  Baetis prefer warmer water than the midges.  As such, they are found in greater numbers downstream of the Texas Hole and are more prolific as you reach the lower stretches of the quality water.
Notes The Baetis is also known as a Mayfly.  Baetis nymph patterns are productive fished near the bottom early right before the typical hatch times (around 11am or so) and in between hatches throughout the afternoon.  Fish tend to key in on the baetis just as they reach the surface and begin to emerge and are helpless and still.  When hatches are significant, the fish may key in on the adult stage.  Hatches are best in April/May and October/November and are especially good during overcast conditions.

My favorite tactic for fishing a good baetis hatch is to rig up with an olive sparkle dun or parachute adams trailed by a gray or olive RS-2 with a CDC wing.  Present the fly downstream to the rising fish so the fish sees the fly before the leader.  Make sure you put it right over the fish's nose.   Often it pays to focus in on a single rising fish and try to determine its feeding rhythm before making a cast.

Fly Patterns Select Baetis under the Fly Patterns link  for recipes and pictures of the patterns.