Ephemera simulans

Distinguished from the closely related Green Drake (Ephemera guttulata) by timing and habitat overlap rather than morphology; the two species frequently co-occur in trout streams with simultaneous hatches. Adults identified by upright wing posture after mating, which fish selectively target over outstretched-wing individuals. Artificial fly patterns emphasize silhouette and presentation over exact color matching. The common name "Brown Drake" is shared with Hexagenia atrocaudata, requiring care in identification context.

Freshwater lakes and streams with sand and silt bottoms. Nymphs burrow in clay, silt, sand, and gravel substrates, showing preference for mixed matrix bottoms over pure silt/clay. Documented from lacustrine environments including Dauphin Lake, Manitoba and Lake Wawasee, Indiana, as well as flowing trout streams in the Rocky Mountains and Midwest.

North America: widespread across the United States including the Rocky Mountains, Midwest, and Great Lakes region. Most common mayfly species in family Ephemeridae in North America. Documented occurrences in Vermont, Manitoba, and Indiana. Annual hatches reported from Skaneateles Lake, New York.

Adults emerge from mid-June to mid-July. Both hatching and mating occur at night. Nymphs present year-round in substrates.

Life cycle duration has been a subject of study; related genus Hexagenia reported to take two years in Lake Winnipeg. Nymphs develop in bottom substrates, emerging at night to ride the water surface until wings dry and flight is possible. Emergence period spans approximately one month in mid-summer.

Nymphs are burrowers, constructing and occupying U-shaped tunnels in sand and silt. Emergence behavior involves nymphs rising from substrates and riding the water surface, making them highly vulnerable to predation during this stage. Adults hold wings upright after mating, a posture that increases predation risk from fish. Mating and hatching both occur nocturnally.

Important component of benthic production in freshwater ecosystems. Annual production estimates from Dauphin Lake, Manitoba ranged from 9.02 to 9.90 g/m² (wet weight). Serves as significant prey for trout, bass, perch, rock bass, Atlantic salmon, and bullheads. High vulnerability during emergence makes it a critical food source for sport fish.

Nationally important species for recreational fly fishing on premier trout streams. Artificial nymph patterns include the Wiggle Nymph, Marabou Nymph, and Feather Duster nymph. Adult patterns emphasize silhouette and presentation over color accuracy. Attracts anglers regionally, with fishermen traveling to Central New York specifically for Skaneateles Lake hatches.

• Ephemera guttulata (Green Drake)Co-occurs in trout streams with simultaneous hatches; similar ecology and habitat use, distinguished by common name reference and potentially coloration, though exact morphological differences not specified in sources.
• Hexagenia atrocaudataShares common name "Brown Drake," creating identification confusion; different genus within same order.

• mayfly
• Ephemeroptera
• Ephemeridae
• burrowing mayfly
• fly fishing
• Brown Drake
• North America
• benthic invertebrate
• trout food
• nocturnal emergence

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