Western Iron Dun vs Mountain Flathead Mayfly

Side-by-side species comparison

Attribute Western Iron Dun Mountain Flathead Mayfly
Scientific Name Epeorus longimanus Cinygmula ramaleyi
Order Ephemeroptera Ephemeroptera
Family Heptageniidae Heptageniidae
Size 10-14 mm 7-10 mm
Habitat Rivers & Streams Mountains
Diet Omnivores Omnivores
Regions North America North America
Conservation Least Concern Least Concern

Western Iron Dun

An iconic eastern mayfly that signals the start of spring fly-fishing season. Nymphs have only two tails and cling to rocks in fast current.

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Did You Know?

It was named after Theodore Gordon, considered the father of American dry-fly fishing.

Mountain Flathead Mayfly

An alpine mayfly restricted to high-elevation cold streams in the Rocky Mountains. Nymphs feed on diatom films on boulder surfaces.

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Did You Know?

This species cannot survive in water temperatures above 15 degrees Celsius.