A female subimago of a March Brown mayfly (Rhithrogena germanica). Mayflies belong to the order Ephemeroptera, and the only insects that have a subimago phase. This stage is a favourite food of many fish, and many fishing flies are modeled to resemble them. They are aquatic insects whose nymph stage usually lasts one year in freshwater. The adults are short-lived, from as little as thirty minutes to a few days depending on the species.Photo credit: Richard Bartz
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