mayfly

noun

may·​fly ˈmā-ˌflī 

: 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

Examples of mayfly in a Sentence

Recent Examples on the Web

The thick mats cover up the rocky streambed where invertebrates like mayfly nymphs like to live, and instead creates habitats for smaller insects, chironomids and worms. — Hannah Smith july 25, Idaho Statesman, 25 July 2026

While the lights themselves aren’t drawing in spiders, the moths, gnats, mosquitoes, and mayflies bobbing around the lights do. — Karen Brewer Grossman, Southern Living, 9 July 2026

The Minnesota Department of Transportation says an exploding population of mayflies could cause serious trouble for drivers in southeast Minnesota. — Frankie McLister, CBS News, 12 June 2026

To make the distinction, midges are often smaller and mayflies have a more upright wing posture, according to NexGreen. — Sarah Moore, Freep.com, 28 May 2026

Word History

First Known Use

circa 1653, in the meaning defined above

Kids Definition

mayfly

noun

may·​fly -ˌflī 

: any of a group of insects that as adults live only a short time and have fragile wings