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

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.

Dorsal view of a Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Nymph from the East Fork Issaquah Creek in Washington
This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
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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Caddisfly Species Helicopsyche borealis (Speckled Peters)

This is the only important trout stream species of Helicopsyche. It has an unusual wing characteristic, described by Gary LaFontaine in Caddisflies:

The adult appears different in flight from other caddisflies because the top set of wings is attached to the bottom by a row of hooks, so the four wings beat together, not as two spread-out sets.

Where & when

Time of year : Early May through July

Preferred waters: Rivers or lakes; best in spring creeks and large rivers

The emergence of this species lasts a few weeks in any given location. It begins in the East in early May and lasts through June, while in the West it begins in mid-June and lasts through early July.

In 137 records from GBIF, adults of this species have mostly been collected during June (23%), July (21%), August (19%), May (12%), September (9%), and April (8%).

In 92 records from GBIF, this species has been collected at elevations ranging from 195 to 10194 ft, with an average (median) of 3509 ft.

Species Range

Hatching behavior

Time of day : Evening

Egg-Laying behavior

Time of day: Evening

LaFontaine gives a slightly confusing account of the ovipositing behaivor of this species in Caddisflies, suggesting that they may flutter around on or near the water's surface looking for solid objects to attach their eggs to, or may drop them in the water. Swisher and Richards give a clearer picture in Selective Trout:

During egg laying, the females float in the surface close to the banks, crawl underwater, and flop on the surface to oviposit. They then ride the water serenely in the normal resting position, and trout take them with gentle rises.

Larva & pupa biology

Diet: Algae, detritus, animal matter

Environmental tolerance: Very tolerant: can thrive in both cold water and hot springs up to 110°F

Shelter type: Coiled sand case shaped like a snail shell

Specimens of the Caddisfly Species Helicopsyche borealis

1 Female Adult
1 Pupa

Start a Discussion of Helicopsyche borealis


Caddisfly Species Helicopsyche borealis (Speckled Peters)

Species Range
Common Name
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