Why do cockchafers have such weird, feathery antennae?

Cockchafers, along with stag beetles, dung beetles, dor beetles and scarabs, have the last three to seven segments of their antennae expanded into flat, plate-like leaves, which sit in a distinctive fan-like arrangement.

Antennae are the olfactory sense organs of insects, and this formation greatly increases the surface area available for the chemosensors.

Insects usually need to sniff out two things – food sources and mates.

In dung beetles, male and female antennae are very similar, suggesting that both are attracted to faecal odours, so can locate a mate at a pat.

Male and female cockchafers may use some subtle chemical signal from decay, or particular roots, to co-ordinate a rendezvous, but the fact that males have seven club segments and females only six suggests that males also respond to female pheromone scents.