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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.

Lateral view of a Male Baetidae (Blue-Winged Olive) Mayfly Dun from Mystery Creek #308 in Washington
This dun emerged from a mature nymph on my desk. Unfortunately its wings didn't perfectly dry out.
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 Rhyacophila grandis (Green Sedges)

This is an especially large species of Rhyacophila, with a maximum size of 30mm.

Where & when

Time of year : February to August

Preferred waters: Small streams

In 44 records from GBIF, adults of this species have mostly been collected during June (39%), July (30%), May (11%), August (9%), and September (7%).

In 8 records from GBIF, this species has been collected at elevations ranging from 69 to 1083 ft, with an average (median) of 354 ft.

Species Range

Rhyacophila grandis Fly Fishing Tips

Gary LaFontaine notes in Caddisflies that imitataions of these larvae work well during non-hatch periods because the widely spread emergence dates mean the mature larvae are available year-round.

Start a Discussion of Rhyacophila grandis


  • LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.

Caddisfly Species Rhyacophila grandis (Green Sedges)

Species Range
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