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*** Note: KnowYourInsects.org does its best to include correct identifications of insect photos. It’s always possible that we made a mistake, however, so if you see a misidentification, please contact us and we will correct it. Thanks!

Order Ephemeroptera: the mayflies — Examples
For more information, see the article: “How to Survive a Massive Mayfly Swarm” on the Entomological Society of America’s blog Entomology Today.

Families represented below:
Baetidae Ephemeridae Heptageniidae Palingeniidae Polymitarcyidae Additional Mayflies

Ephemeridae, the common burrower mayflies
Palingeniidae, the riverbed burrower mayflies

Subimago mayfly
Mayfly, possibly giant mayfly, Hexagenia limbata, family Ephemeridae (the common burrower mayflies).
□ Adult mayflies have no functioning mouths or digestive systems, but that’s OK, because they only live a day or so — long enough to mate and lay eggs. Most of the mayfly’s life is spent underwater as a youngster (naiad). Most naiads eat algae and vegetation, although a few species will eat other little critters in their freshwater environment.
Photographed and identified as a mayfly by: Lauryn Filby. Location: De Soto, Kansas, USA. Date: 8 July 2016.
Lauryn says, “This specimen lacks significantly dark characteristics. It may be younger which would cause a lack of pigmentation.”
Subimago mayfly
Mayfly, possibly giant mayfly, Hexagenia limbata, family Ephemeridae (the common burrower mayflies).
□ Anglers abbreviate the giant mayfly’s scientific name of Hexagenia limbata to simply Hex. This species often emerges from the water en masse in a “hex hatch.” Fish go into a feeding frenzy when the hatch is underway, so it is a good time to get out the fishing rod.
Photographed and identified as a mayfly by: Lauryn Filby. Location: De Soto, Kansas, USA. Date: 8 July 2016.
Subimago mayfly
Mayfly, possibly giant mayfly, Hexagenia limbata, family Ephemeridae (the common burrower mayflies).
□ Anglers abbreviate the giant mayfly’s scientific name of Hexagenia limbata to simply Hex. This species often emerges from the water en masse in a “hex hatch.” Fish go into a feeding frenzy when the hatch is underway, so it is a good time to get out the fishing rod.
Photographed and identified as a mayfly by: Lauryn Filby. Location: De Soto, Kansas, USA. Date: 8 July 2016.
Mayfly (Hexagenia)
Mayfly, possibly giant mayfly in the genus Hexagenia, family Ephemeridae (the common burrower mayflies).
Giant mayflies hatch altogether in early July in Tennessee, where this photo was taken. The photographer described “groups of thousands.” A feature of the giant mayflies is the thin, dark border on the hind wing.
Photographed by: Youssef Eryan. Identified by: KnowYourInsects.org. Location: Nashville, Tennessee, USA. Date: 13 July, 2020.
Green Drake (Ephemera danica)
Green Drake, Ephemera danica, family Ephemeridae (the common burrower mayflies).
□ This large green drake has a body about an inch (2.5 cm) long, and tails that can extend another 2 inches (5 cm).
□ As a naiad (immature), this insect lives in at the bottom of clean lakes, and fast-moving rivers and streams. The similar and closely related species Ephemera vulgata has naiads that live in still water, such as stagnant ponds, and can survive even in polluted water.
Photographed and identified to order by: Ellie Russell. Identified to species by: KnowYourInsects.org. Location: Lough Derg, Ireland. Date: 3 June, 2021.
Ellie says, “We saw this fly on our car today beside Lough Derg looking out at Holy Island.”

Polymitarcyidae, the pale burrowers

Pale Burrower Mayfly, Ephoron virgo
Pale burrower, Ephoron virgo, family Polymitarcyidae (the pale burrowers).
Pale burrower is an apt name for this mayfly. With its light-tan coloration, it is definitely pale, and the aquatic larva digs a tunnel in the substrate underwater. The larva lives in the tunnel, using its gills to fan water — and prey (smaller invertebrates) — past.
Photographed by: Ingmar Janssen. Identified by: KnowYourInsects.org. Location: The Netherlands. Date: 20 July, 2018.
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Heptageniidae, the flat-headed mayflies

Flat-Headed Mayfly, Heptagenia culacantha
Flat-headed mayfly, Heptagenia culacantha, family Heptageniidae (the flat-headed mayflies).
□ First discovered in 1985, this species of flat-headed mayfly is a rare and quite beautiful mayfly. It is found in a small area of New York and Pennsylvania.
□ It is a large mayfly with a body length of about an inch (2.5 cm), and that is not counting the long cerci (the “tails.”
Photographed by: Sam Decker. Identified by: Tony Ertola. Location: Delaware River near Long Eddy, New York, USA. Date: June, 2020.
Flat-Headed Mayfly, Heptagenia culacantha
Flat-headed mayfly, subimago, Heptagenia culacantha, family Heptageniidae (the flat-headed mayflies).
□ This is the subimago of a flat-headed mayfly, which means that it is in the stage just before it will become a reproductively capable adult. Anglers often call the subimago a “dun.” Mayflies are unusual among the insects in having a non-adult that is capable of flight.
Photographed and identified by: Tony Ertola. Great find and identification, Tony! Location: Delaware River near Long Eddy, New York, USA. Date: June, 2016.
Tony says, “I wish the pic was clearer.” KnowYourInsects.org says, “We are just thrilled you got a photo at all, Tony!”
Flat-Headed Mayfly, Heptageniidae
Flat-headed mayfly, possibly in the genus Stenacron, family Heptageniidae (the flat-headed mayflies).
□ This flat-headed mayfly has huge eyes and very long cerci (the double “tail”).
Photographed by: Denise Rulason. Identified by: KnowYourInsects.org. Location: Interlochen, Michigan, USA. Date: 24 June, 2018.

Baetidae, the small minnow mayflies

Baetid Mayfly
Mayfly, family Baetidae (the small minnow mayflies).
□ This is a tiny mayfly, probably in the family Baetidae. A new species of Mayfly in the Baetidae family was discovered recently in India — just 4-5 mm long and with only one pair of wings rather than the typical two pairs. Information on this new species (Labiobaetis soldani is available here.
Photographed and identified to order by: Dr. Somashekhara Achar. Identified to family by: KnowYourInsects.org. Location: Tumkur, Southern Karnataka, India. Identified by: KnowYourInsects.org. Date: 22 February, 2020.
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Additional unidentified mayflies

Mayfly swarm
Mayfly swarm, family unidentified, order Ephemeroptera (the mayflies).
□ The little white specks are all mayflies — a big swarm! They were attracted by the lights on the bridge in this photo from Indonesia.
Photographed by: Galuh Prasetyawan. Identified by: KnowYourInsects.org. Location: Indonesia. Date: 25 January 2017.
Galuh says the mayflies swarmed at dusk, caused slippery driving conditions when they landed on the road surface, and “a lot of motorcycles fell.”
Adult mayfly
Mayfly, family unidentified, order Ephemeroptera (the mayflies).
□ This is a closeup of a mayfly — a swarm of them is shown in the previous photo.
Photographed by: Galuh Prasetyawan. Location: Indonesia. Identified by: KnowYourInsects.org. Date: 25 January 2017.
Mayfly
Mayfly, family unidentified, order Ephemeroptera (the mayflies).
□ Nearly all mayfly species have two pairs of wings: one large front pair (the forewings), and one much-smaller pair (the hindwings). See if you can see the hindwings on any of the adult mayflies on this page.
Photographed and identified by: Dayana Gonzalez-Saez. Location: Connecticut, USA. Date: 25 May, 2017.
Adult mayfly
Mayfly, adult, family unidentified.
Photographed and identified by: Simon Adams. Location: Colchester, England. Date: 4 June 2014.
Mayfly adult and casing
Mayfly, adult and exuviae (shed casing), family unidentified.
□ The one on the left is an adult mayfly that may have hatched out of the casing (or exuviae) on the right. With these insects, the young (naiads) live underwater for many months. When they are ready to turn into adults, they get wings, swim up out of the water and onto the land, and molt one last time into adults. The adults live only 1-2 days.
Photographed by: Christie Remaly. Identified by: KnowYourInsects.org. Location: Club Deb in Knoxville, Tennessee, USA. Date: 6 July 2018.
Mayfly casing
Mayfly, exuviae (shed casing), family unidentified.
□ This is the shed casing, or exuviae, of a winged but immature mayfly. Such an immature mayfly is called a subimago. The adult mayfly emerges and leaves behind this exuviae. Mayflies are unusual in that they have an immature version that has functional wings. (Among other winged insects, only the adults have functional wings.) Fly fishermen call the immature, winged mayflies “duns.”
Photographed by: Lori Sughroue. Identified by: Kelly McKinne (@gonzonaturalist). Location: Elk Rapids, Michigan, USA. Date: 31 August 2016.
Lori says, “There were dozens of these in varying sizes, approximately half an inch to this one, about three inches long.”
Mayfly
Mayfly, exuviae, family unidentified.
□ Look at the amazingly long cerci (the two “tails”) on this shed casing of a mayfly!
Photographed by: Victoria Abbott. Identified by: KnowYourInsects.org. Location: United Kingdom. Date: 26 July, 2017.
Victoria says, “I was wondering if you could help ID this wonderful insect. My friend found it on her shed today in the UK. Would be absolutely tremendous to find out what it is.” KnowYourInsects.org loves Victoria’ enthusiasm and we’re happy to help!
Mayfly
Mayfly, exuviae, family unidentified.
□ The photographer found this near the shore of Lake Erie in the fall. It had a half-inch-long (1.25cm) body and inch-long (2.5cm) “tails” (cerci). This is the exuviae, or the shed casing of a mayfly. Most mayfly species metamorphose from nymph to adult earlier in the year, but a few species hold out until late summer and early fall.
Photographed by: Jack Hawkins. Identified by: KnowYourInsects.org. Location: Southern Ontario, Canada. Date: fall 2017.
Jack says, “In my travels, I saw straw tail birds with a 12- to 14-inch (30-35 cm) straw-like appendage. It was on an island like Mauritius or Seychelles Islands. (This) bug reminded me of the bird!”
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