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.

Stream photos

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Female Hydropsyche (Spotted Sedge) Caddisfly Adult Female Hydropsyche (Spotted Sedge) Caddisfly Adult

Lateral view of a Female Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Adult from the Columbia River in Washington

7 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.

Caddisfly Genus Hydatophylax (Giant Cream Pattern-Wing Sedges)

These are huge caddisflies. The larvae may be nearly an inch and a half long and build three-inch cases. Hook sizes 4-6 are appropriate for the pupae.

Where & when

Time of year : Late May to fall in the East; August to October in the West

Preferred waters: Medium to large streams

In 69 records from GBIF, adults of this genus have mostly been collected during June (46%), July (22%), May (19%), and August (7%).

In 14 records from GBIF, this genus has been collected at elevations ranging from 33 to 2740 ft, with an average (median) of 2008 ft.

Genus Range

source

Map of specific collection sites

Hatching behavior

Time of day : Morning

Trout may feed on the pupae of this genus.

Egg-Laying behavior

The egg-laying adults are not important.

Larva & pupa biology

Diet: Woody debris

Current speed: Slow

Specimens of the Caddisfly Genus Hydatophylax

1 Female Adult

Female Hydatophylax argus (Giant Cream Pattern-Wing Sedge) Caddisfly Adult

12 Pictures

Lateral view of a Female Hydatophylax argus (Limnephilidae) (Giant Cream Pattern-Wing Sedge) Caddisfly Adult from the Teal River in Wisconsin

I had some trouble working through the genus key for this one because I'm not great at interpreting caddis wing venation. Fortunately, figure 19.707 in An Introduction to the Aquatic Insects of North America (Fifth Edition) shows the distinctive color pattern of the striking forewings on Hydatophylax argus, which is a perfect match for the pattern as well as venation. As there are no other species in that genus in this area, I can be pretty confident in the species ID.

Collected June 10, 2021 from the Teal River in Wisconsin

Added by Troutnut on June 12, 2021

Collected June 10, 2021 from the Teal River in Wisconsin and added by Troutnut on June 12, 2021

Start a Discussion of Hydatophylax

References

LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
Merritt R.W., Cummins, K.W., and Berg, M.B. 2019. An Introduction to the Aquatic Insects of North America (Fifth Edition). Kendall/Hunt Publishing Company.
Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.