Common Mayfly vs Riffle Beetle

Side-by-side species comparison

Attribute Common Mayfly Riffle Beetle
Scientific Name Ephemera danica Elmis aenea
Order Ephemeroptera Coleoptera
Family Ephemeridae Elmidae
Size 15-25 mm body 1.5-2.5 mm
Habitat Rivers & Streams Rivers & Streams
Diet Detritivores Detritivores
Regions Europe Europe
Conservation Least Concern Least Concern

Common Mayfly

Adults have no functional mouths and live only 1-3 days. Massive synchronized emergences called "hatches" are among natures great spectacles. Excellent water quality indicators.

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Did You Know?

Mayflies have the shortest adult lifespan of any insect — some species live just 5 minutes as adults, long enough only to mate. They are the only insects with a winged sub-adult stage.

Riffle Beetle

A tiny, dark beetle that spends its entire adult life underwater clinging to rocks in riffles. It breathes using a plastron, a permanent thin film of air.

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Did You Know?

Its plastron air film never needs replenishing, allowing it to remain permanently submerged.