may·​fly ˈmā-ˌflī How to pronounce mayfly (audio)
: any of an order (Ephemeroptera) of insects with an aquatic nymph and a short-lived, fragile adult lacking mouthparts and having membranous, heavily veined wings and two or three long, threadlike tails

Note: the wings of the mayfly are held vertically above the body when closed.

called also ephemerid

Illustration of mayfly

Illustration of mayfly

Examples of mayfly in a Sentence

Recent Examples on the Web How: Nymphs that mimic early stoneflies and Baetis mayflies are always safe bets; however, Demalderis cautions not to rule out streamers. Joe Cermele, Field & Stream, 14 Mar. 2024 Throughout the spring and summer months, cutthroat will eagerly take flies ranging from caddis, mayfly and stonefly imitations to terrestrials like ants, grasshoppers and woolly worms. Jordan Rodriguez, Idaho Statesman, 31 Jan. 2024 Some insects, including stoneflies, mayflies, caddisflies and non-biting midges, are active in the winter months. John Myers, Twin Cities, 6 Jan. 2024 Here is the mayfly on my hand bringing itself into synch with my biorhythms. John Kinsella, The New Yorker, 11 Dec. 2023 On that warm midsummer morning, Stoke Abbott was all biscuit-colored loveliness in thatch and sandstone, with dog roses panting out of the hedges, mayflies shimmering, and bees rummaging in the foxgloves. Catherine Fairweather, Travel + Leisure, 28 Aug. 2023 There are at least 126 species in Michigan, with the giant mayfly one of the most widely distributed, according to a 2020 article by David Lowenstein with Michigan State University Extension. Christina Hall, Detroit Free Press, 29 July 2023 Tailwaters tend to produce prolific hatches of small mayflies, and their trout tend to refuse flies that don’t imitate the real thing. Morgan Lyle, Field & Stream, 13 July 2023 Michigan is home to countless species of fish flies, also known as mayflies, and many are expected to swarm lakeside communities near Lake Erie, Lake St. Clair and the Detroit River in the days to come. Marina Johnson, Detroit Free Press, 22 June 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mayfly.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

circa 1653, in the meaning defined above

Time Traveler
The first known use of mayfly was circa 1653

Dictionary Entries Near mayfly

Cite this Entry

“Mayfly.” Dictionary, Merriam-Webster, Accessed 12 Apr. 2024.

Kids Definition


may·​fly -ˌflī How to pronounce mayfly (audio)
: any of a group of insects that as adults live only a short time and have fragile wings

More from Merriam-Webster on mayfly

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