Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York

Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

The trees were leafing out and the trout were rising on this productive Wisconsin stream

From the Namekagon River in Wisconsin

Stream photos

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Neoleptophlebia Mayfly Nymph Neoleptophlebia Mayfly Nymph

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington

Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.

10 Recently Added Photos

27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.

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Updates from July 26, 2011

Closeup insects by Bnewell from the Touchet River in Washington

Hydropsychidae Caddisfly Adult

2 Pictures

These specimens are either Cheumatopsyche or Hydropsyche. They escaped before I could catch them.I suspect, based on size, they are Hydropsyche, they are about 1/4 inch in length. Both H. occidentalis and H. californica are common in the Touchet River.

Collected July 26, 2011 from the Touchet River in Washington

Added by Bnewell on July 29, 2011

Collected July 26, 2011 from the Touchet River in Washington and added by Bnewell on July 29, 2011

Female Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner

1 Picture

Female Acentrella turbida (Baetidae) (Tiny Blue-Winged Olive) Mayfly Spinner from the Touchet River in Washington

Here is the female spinner of the tiny Acentrella turbida. You can see the coloration is quite different from the male.

Collected July 26, 2011 from the Touchet River in Washington

Added by Bnewell on July 29, 2011

Collected July 26, 2011 from the Touchet River in Washington and added by Bnewell on July 29, 2011

Male Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner

3 Pictures

Male Acentrella turbida (Baetidae) (Tiny Blue-Winged Olive) Mayfly Spinner from the Touchet River in Washington

I would not like to have to match this hatch. These are the smallest mayflies I have ever seen. I used to think Caenis was the smallest adult mayfly in the west but these guys are about 4mm long. The male eyes are two toned, brown above and olive below. The abdomen is dark brown interspersed with light brown. The abdomen is clear for the anterior 2/3rd and the remainder is white. The tails are twice as long as the insect. There is only one pair of wings.

Collected July 26, 2011 from the Touchet River in Washington

Added by Bnewell on July 27, 2011

Collected July 26, 2011 from the Touchet River in Washington and added by Bnewell on July 27, 2011