mayfly

American  

[mey-flahy] / ˈmeɪˌflaɪ /

noun

• mayflies
  plural

1. Also called shadfly.  any insect of the order Ephemeroptera, having delicate, membranous wings with the front pair much larger than the rear and having an aquatic larval stage and a terrestrial adult stage usually lasting less than two days.

2. Angling. Also May fly an artificial fly made to resemble this insect.

---

mayfly British  

/ ˈmeɪˌflaɪ /

noun

1. Also called: dayfly.  any insect of the order Ephemeroptera (or Ephemerida ). The short-lived adults, found near water, have long tail appendages and large transparent wings; the larvae are aquatic

2. angling an artificial fly resembling this

---

Other Word Forms

Noun Inflected Forms

• mayflies
  plural

Etymology

Origin of mayfly

First recorded in 1645–55; May + fly ¹

Example Sentences

See Examples For:

mayfly mayflies

"In some cases we've got a 90% reduction in one particular mayfly species and also in one particular caddisfly, and a 30% reduction in two other mayfly species."

From BBC ● Mar. 10, 2026

Many of these evanescent would-be Utopias, independent communes and mayfly principalities hardly did more than design a flag and choose a national anthem.

From Washington Post ● Jun. 22, 2021

But as far as each audience is concerned, it’s also a mayfly.

From Seattle Times ● May 8, 2019

The Stroud Water Research Center in Pennsylvania, where Jackson is based, has a long tradition of testing water quality impacts on mayfly larvae.

From Scientific American ● Dec. 6, 2018

I am going to make my mayfly life count for something.

From "The Cruel Prince" by Holly Black

The plump mayflies known as green drakes were emerging on the water.

From The Wall Street Journal ● Jul. 5, 2026

Crucially, the data show that families that are particularly sensitive to river pollution, like mayflies, stoneflies and caddisflies, are recovering most strongly of all.

From Science Daily ● Oct. 4, 2023

The American Southeast has the greatest aquatic biodiversity of anywhere in the temperate world, with an amazing array of fish, mussels, aquatic snails, crawdads and aquatic insects, like mayflies and dragonflies.

From Seattle Times ● Oct. 21, 2022

Aquatic insects, such as caddisflies and mayflies, though, are adapted to natural seasonal flooding and lay eggs just below the surface of the water.

From New York Times ● Aug. 2, 2022

There would be no large stoneflies, no mayflies, no caddis flies.

From "Silent Spring" by Rachel Carson