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.

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

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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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Thinking this is distinctus, but not sure

DayTripper

Northern MI

Posts: 70

DayTripper on Jul 2, 2009July 2nd, 2009, 1:13 am EDT

Found this female dun on the East Branch of the Delaware the first weekend in June. It was ~30mm long. I'm pretty sure it's a female distinctus dun, but was hoping someone could confirm. Thanks.

GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681

GONZO on Jul 2, 2009July 2nd, 2009, 4:41 am EDT

Alex,

This is Ephemera varia. A 30mm size estimate is well above what is typical for either E. varia or A. distinctus, though the size range for varia is underestimated in books like Hatches and Mayflies. They give 13-16mm as the range for both species, but the varia females that I've collected from the Yellow Breeches run between 17-20mm.

DayTripper

Northern MI

Posts: 70

DayTripper on Jul 2, 2009July 2nd, 2009, 5:12 am EDT

Thanks Gonzo, I really appreciate it. I knew it had to be one of the two (distinctus or varia), but as you mentioned, the large size didn't fit what my reference books had listed. I know looking at coloration is a no-no when identifying bugs, but the coloration seemed more of a match to the distinctus color plate in Hatches, so I ran with it. Thanks, again.