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 North Fork Couer d'Alene River in Idaho

Stream photos

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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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Female Amphinemura (Tiny Winter Black) Stonefly Adult Pictures

A few of these tiny stoneflies were among the only species of aquatic insect adults in the air on this particular afternoon, with most of the action coming from a species of Epeorus mayfly. I somehow forgot to photograph this one on the usual ruler, but I recall it was very, very small, with an abdomen no more than 1mm in girth and the body, not counting the wings, probably just 5-7mm long.

Ventral view of a Female Amphinemura (Nemouridae) (Tiny Winter Black) Stonefly Adult from Mystery Creek #23 in New York

Dorsal view of a Female Amphinemura (Nemouridae) (Tiny Winter Black) Stonefly Adult from Mystery Creek #23 in New York

Female Amphinemura (Nemouridae) (Tiny Winter Black) Stonefly Adult from Mystery Creek #23 in New York

Lateral view of a Female Amphinemura (Nemouridae) (Tiny Winter Black) Stonefly Adult from Mystery Creek #23 in New York

This stonefly was collected from Mystery Creek #23 in New York on September 6th, 2006 and added to Troutnut.com by Troutnut on October 3rd, 2006.

Discussions of this Adult

Small stonefly photos

9 replies

Posted by JaneBug on Jan 25, 2007

Last reply on Jan 28, 2007 by DMM

The stonefly in this series of photos is not a Capniidae. It is a Nemouridae, a female Amphinemura. The yellow abdomen has eggs inside. Message from a stonefly researcher from Pennsylvania.

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