A mayfly, especially any insect belonging to the order Ephemeroptera or the family Ephemeridae.
From Ephemeridae, the family name of mayflies, from Greek ephemeros 'lasting a day' plus the suffix -id (indicating family membership in taxonomy).
A mayfly is called an 'ephemerid' because adult mayflies live for mere hours—some species exist as flying adults for less time than it takes you to watch a movie.
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