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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Holocentropus Caddisfly Larva Holocentropus Caddisfly Larva

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington

This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.

11 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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Ontario Sallfly

Sweltsa onkos (Sallfly) Stonefly Adult

8 Pictures

Dorsal view of a Sweltsa onkos (Chloroperlidae) (Sallfly) Stonefly Adult from Mystery Creek #62 in New York

Collected May 14, 2007 from Mystery Creek #62 in New York

Added by Troutnut on May 18, 2007

Collected May 14, 2007 from Mystery Creek #62 in New York and added by Troutnut on May 18, 2007

GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681

GONZO on Sep 9, 2008September 9th, 2008, 3:36 pm EDT

I believe this is probably Sweltsa onkos. There are three Sweltsa species commonly listed for most of the Northeast (onkos, naica, and lateralis), and their individual pronotum/head markings seem rather distinctive.