Ephemera guttulata

The eastern green drake is among the largest mayfly species in eastern North America. Adults can be distinguished by their size and coloration, though specific diagnostic features are not detailed in available sources. The subimago (dun) stage has wings, while the fully mature imago (spinner) stage represents the final reproductive form. Larvae are burrowers in sandy or muddy substrates.

Larvae inhabit freshwater systems with sandy or muddy bottoms where they construct burrows. The species is associated with rivers and streams suitable for burrowing behavior.

Endemic to the eastern seaboard of the United States and Canada. Range extends west to Ontario and Arkansas but no farther. Present throughout the continental United States and Canada within this eastern zone.

Larvae are filter-feeders and collectors, consuming organic particles and detritus from the water column and substrate. Specific dietary details for adults are not documented; adult mayflies typically do not feed.

The life cycle consists of three stages: a fully aquatic larval stage, a flying sexually immature adult stage called the subimago (or dun), and a short-lived sexually mature adult stage (imago). Larvae are aquatic burrowers. The subimago molts into the imago, which mates and dies shortly after.

Larvae construct and inhabit burrows in sandy or muddy stream bottoms. Adults are known for synchronous mass emergence events that create significant feeding opportunities for fish. The subimago stage must sit on the water surface to allow wings to dry before flight, making them vulnerable to predation.

Larvae function as benthic detritivores and filter-feeders, processing organic matter in freshwater ecosystems. Both larval and adult stages serve as critical prey for fish, particularly trout. Mass emergence events represent major nutrient pulses linking aquatic and terrestrial food webs.

Highly significant to recreational fly fishing. The species is considered one of the most important hatches in eastern North American trout streams. Anglers use specialized fly patterns to imitate the dun and spinner stages. Multiple common names reflect its importance: "eastern green drake," "shad fly," and "coffinfly."

• Ephemera simulansAnother large burrowing mayfly in the same genus; both species are important to anglers and require careful imitation with specific fly patterns.
• Hexagenia limbataLarge mayfly species with mass emergence events important to anglers; distinguished by different genus affiliation and typically different habitat preferences (Hexagenia often in lakes, Ephemera in rivers).

• mayfly
• Ephemeroptera
• fly fishing
• aquatic insect
• trout food
• burrower
• eastern North America

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
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