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.

I caught a nice brookie a few weeks earlier in this pool at the junction of a split channel in the stream. The huge fallen tree is great cover.

From the Mystery Creek # 23 in New York

Stream photos

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Limnephilus (Summer Flier Sedge) Caddisfly Larva Limnephilus (Summer Flier Sedge) Caddisfly Larva

Case view of a Limnephilus (Limnephilidae) (Summer Flier Sedge) Caddisfly Larva from the Yakima River in Washington

This seems to be a young larva of Limnephilus. Although not clear in the picture, several ventral abdominal segments have chloride epithelia.

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 Species Hydatophylax argus (Giant Cream Pattern-Wing Sedges)

This is an especially large species, with pupae and adults up to hook size 2.

Where & when

Time of year : June through fall

Preferred waters: Small streams

In 53 records from GBIF, adults of this species have mostly been collected during June (55%), May (21%), and July (19%).

In 13 records from GBIF, this species has been collected at elevations ranging from 627 to 2740 ft, with an average (median) of 2008 ft.

Species Range

source

Map of specific collection sites

Hatching behavior

Time of day : Morning

Gary LaFontaine reports in Caddisflies that his trout stomach samples held many Hydatophylax argus pupae during their emergence in the East.

Specimens of the Caddisfly Species Hydatophylax argus

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 argus

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.