The upper wings of both sexes are bronzy or metallic greenish, close along the body.

The males have very long thread-shaped whitish antennas, forward-facing and reaching about four times the length of the body.

[4][9] If a female flies through the swarm, it is caught by a male and the mating in flight takes place.

They protect themselves for the summer and winter in an oblong, brown bag-like structure of small pieces of fallen leaves.

[5] The name honours the French naturalist René Antoine Ferchault de Réaumur.