What does mayfly mean?
A mayfly is a small aquatic insect with two or more tail-like appendages and extremely brief adult life. Its nymphal stages live in freshwater, often for a year or longer, before the insects emerge into a winged adult form. The adults generally survive only hours or a few days, though they may mate and lay eggs during that time. The name combines “may” and “fly,” reflecting the traditional association of the insect’s seasonal appearance with May and, more generally, its fleeting life. In figurative use, “mayfly” describes anything lasting only a very short time. The word is also familiar from environmental monitoring, where mayfly nymphs are used as indicators of freshwater quality because many species are sensitive to pollution and changes in water conditions.
nounA small, short-lived winged insect of the order Ephemeroptera, whose adult form usually lives for only a few hours or days. Mayflies undergo a conspicuous emergence from aquatic nymphs, often in large groups.
- Any insect of the order Ephemeroptera, especially one in its short-lived adult stage.
"A swarm of mayflies rose from the river as the evening air warmed."
"The mayflies were attracted to the lights along the riverbank."
"Ecologists monitor mayfly nymphs to assess the health of freshwater ecosystems."
The plural is formed by changing the final y to i and adding -es: mayfly becomes mayflies.
"Large numbers of mayflies gathered around the lights."
A mayfly may spend months underwater, yet its winged adult form may last only a single day.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of mayfly
The English word “mayfly” is a compound of “may” and “fly.” Its name refers to the insect’s appearance around May and its famously brief adult lifespan, although the exact historical reason for the seasonal association is not completely certain. The two elements have separate origins: “may” comes through Old English from a Germanic root related to “might” and “mighty,” while “fly” descends from Old English flyge.
Related word forms
How mayfly is actually used
The term is standard in British and American English. In its figurative use, as in “mayfly existence,” it emphasizes extreme brevity or transience.
Easily confused with mayfly
A mayfly is a delicate insect whose adult life is extremely brief, whereas a dragonfly is a much larger predatory insect that can live for months or years.