Department of Environmental Conservation

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Mayfly (Ephemeroptera)

General Information about Mayflies (Ephemeroptera)
Life history Mayflies, depending on the species, will spend 10 days to 2 years in the water as larvae. Typically larvae of the same kind in the same habitat emerge together on the same day. Their adult stage usually lasts from one to several days at most.
Diversity There are about 23 different families of mayflies in North America.
Distinguishing characteristics Most kinds of mayflies have 3 cerci (tails) and 1 tarsal claw (nail). A few mayflies have only two tails. Some kinds have flat bodies others have round bodies.
Habitat & Feeding Mayflies can be found in fast flowing streams, rivers, ponds and lakes. They can be found in either soft or firm bottom substrates, rocks, aquatic plants, or coarse organic material. Most are scrapers or collector-gatherers; they eat either algae or fine organic material (decaying plant material).
Water quality indicator status Most kinds of mayflies are sensitive to pollution. Usually the presence of mayflies is an indication of good water quality. Mayflies are an excellent indicator because they occupy a diversity of habitats and they are easy to find and usually abundant. Mayfly larvae are part of the widely used EPT Index (Ephemeroptera-Plectoptera-Trichoptera) to measure water quality condition. It is the number of different types of mayflies, stoneflies, and caddisflies.
Fun facts
  • Adult mayflies have non-working mouthparts (they can't eat) and some live for only 90 minutes.
  • Because mayfly larvae emerge together and occasionally with great density in some locations, snowplows have been used to clear the roads of adult mayflies!
image of Isonychiidae
Family: Isonychiidae
image of Leptohyphidae
Family: Leptohyphidae

image of Polymitarcyidae
Family: Polymitarcyidae
image of Caenidae
Family: Caenidae

Image of a Acentrella sp. mayfly.
Family: Baetidae (Acentrella sp.)
Image of a Baetidae mayfly.
Family: Baetidae

Image of a Epeorus sp. mayfly.
Family: Heptageniidae (Epeorus sp.)
Image of a Eurylophella sp.
Eurylophella sp.

image of Ephemeridae
Family: Ephemeridae
image of Leptophlebiidae
Family: Leptophlebiidae

image of Potamanthidae
Family: Potamanthidae