Green Drake

• It belongs to the only insect order that passes through an intermediate winged stage, the subimago: it emerges from the water with wings and able to fly, but is not yet sexually mature and must moult once more.
• Together with stoneflies and caddisflies it forms the so-called "big three" of water-quality assessment: its presence indicates clean water and its disappearance, pollution.
• Mayflies, dragonflies and damselflies are the most primitive winged insects alive: they cannot fold their wings over the abdomen, a trait inherited from the Carboniferous.
• The adult does not feed: its mouthparts are vestigial and it lives four days at most, which is where the genus name Ephemera comes from.
• The proportion is extreme: the nymph spends one or two years, sometimes three, buried in the gravel filtering detritus, in order to fly for barely a few days.
• It is the only insect order that moults once already winged: a dull-winged subimago leaves the water and moults again within hours to give the final imago. Anglers call them the dun and the spinner.
• The female flies just above the water and taps the surface with her abdomen to lay her eggs; when she has finished she falls into the water and dies.
• It is sensitive to pollution, so its presence indicates good water quality.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat & environment

Rivers and streams with gravel beds, where the nymphs dig tunnels and filter organic detritus before emerging in spring into the shallows

Litter / clutch size

The female lays her eggs directly into the water, sometimes dying in the process

Sources consulted: Wikipedia (Ephemera danica); Alba-Tercedor 1990, Life Cycles and Ecology of Some Species of Ephemeroptera from Spain; Brittain 1982, Annual Review of Entomology 27; Revista IDE@-SEA (Orden Ephemeroptera)

Best time: Mainly in May and June, though adults are about between April and November