What do male emperor moths use their feathery antennae to detect?

Male emperor moths use their feathery antennae to detect female pheromones.

The emperor moth, Saturnia pavonia, is a European saturniid moth. Males have broad, feathery antennae with many branches. These branches carry sensory receptors that detect tiny quantities of airborne chemicals released by females. The antennae therefore function as highly sensitive chemical detectors rather than as simple touch organs.

Females are generally larger and less strongly marked in flight, while males have more strongly patterned wings and feathered antennae. Both sexes display prominent eyespots that can startle predators or divert attacks away from the body.

Pheromones are chemical signals used between members of the same species. In moths, female-produced sex pheromones can attract males from considerable distances, allowing a mate to be located even when visual contact is impossible. This is one reason moth antennae are often much more elaborate than butterfly antennae.