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How long do adult mayflies live?

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A mayfly (Ephemera vulgata) with delicate, veined wings and long tail filaments clings to a green blade of grass against a blurred green background. — mayfly An adult mayfly (*Ephemera vulgata*) in Europe.

Adult mayflies are known for their extremely short life spans, typically living for only a few hours after emerging as winged adults. Because their mouthparts and digestive tracts are nonfunctional, they cannot feed during this stage.12

While this brief period is characteristic of the order Ephemeroptera, there are minor variations among species. For instance, some Hexagenia males and females may live long enough to engage in mating activities over two successive days.1

It is important to distinguish this short adult phase from the insect's overall life cycle. Before reaching the adult stage, mayflies spend a significant amount of time as aquatic nymphs, a developmental period that can last from two weeks to two years, with an annual cycle being the most common.12