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.

For how many years, I wonder, have these huge slabs of rock sheltered wild brook trout?

From Mystery Creek # 89 in New York

Stream photos

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Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult

Lateral view of a Female Sweltsa borealis (Chloroperlidae) (Boreal Sallfly) Stonefly Adult from Harris Creek in Washington

I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing 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.

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.

Caddisfly Species Lype diversa (Dark Eastern Woodland Sedges)

Where & when

Time of year : May through July

Preferred waters: Small woodland streams

This species is common in the Midwest and present throughout the East.

In 91 records from GBIF, adults of this species have mostly been collected during June (33%), May (22%), July (20%), and August (12%).

In 59 records from GBIF, this species has been collected at elevations ranging from 39 to 5103 ft, with an average (median) of 1881 ft.

Species Range

source

Map of specific collection sites

Egg-Laying behavior

Time of day: Afternoon or evening

Larva & pupa biology

Gary LaFontaine describes the unusual shelters built by these larvae in Caddisflies:

The larva builds a retreat, or dwelling tube, by raising a simple roof or a groove in a sunken piece of wood. The tube is camouflaged with pieces of detritus and a layer of silk.