Green drake mayfly
Ephemera danica
— Where the name comes from
Ephemera is Greek: epí, upon, and hēméra, the day — “lasting a single day”. It is the same word as “ephemeral”, and this is the species that gave it. The paradox is that the name looks only at the end: the animal lives two or three years underwater and then flies for twenty-four hours, and we have chosen to call it by the length of its shortest part.
— Facts
- Group
- Insects · Insecta
- Order
- Mayflies
- Habitat
- Clean rivers and streams with sandy beds
- Range
- Northern and central Europe
- Size
- 15–25 mm of body; three long tails on the abdomen
- Diet
- Detritus and algae as a nymph; as an adult it does not feed
- Lifespan
- 1–3 years as a nymph, 1–2 days as an adult
— Characteristics
- 01
The adult has no working mouthparts: it cannot feed.
- 02
It is the only insect that moults once more after growing wings.
- 03
The nymphs dig U-shaped burrows in the sand of the bed.
— What sets it apart
It is the only insect in the world that, once winged, moults again. What emerges from the water is called a subimago, already winged but dull and short-legged: it settles on a twig, splits down the back, and out comes the definitive adult, glossy and with very long forelegs that serve to hold the female in flight. The moult leaves on the branch a perfect ghost of the animal, wings included. Then there is a day in which to mate, and it is over: the adult has neither working mouth nor gut, and the presence of its nymphs is used to measure the quality of a river, because they vanish at the first hint of pollution.
