Insects have their senses of touch, smell and taste in their antennae.

Butterflies and Moths have to find the plants they will lay their eggs on by sniffing them out with their antennae.

The Brimstone butterfly lays on Buckthorn or Alder Buckthorn bushes – neither is a very common plant.

Sometimes the females must travel great distances to find them, so their sense of smell must be very acute.

What is more, they are very fussy about which buckthorn bushes they lay on. In one study, in a 150 hectare wood, there were only 12 buckthorn bushes, but 94% of the Brimstone eggs were laid on only two of those 12 bushes! So the butterflies are clearly sensing differences between the bushes.

Search for the Alder Buckthorn bushes that the Brimstones have chosen by looking for the damaged leaves. The caterpillar usually lies along the midrib of the leaf to camouflage itself.

The female Brimstone butterfly produces an aphrodisiac so that the males can find her hidden in the ivy where she has spent the winter in hibernation. Very often several males will be attracted to her even though she is hidden in the leaves.

The antennae of many male moths are very feathery to enable them to sniff out the females at night more efficiently before courtship and mating.

A close-up of a moth antenna taken through a microscope shows just how much greater the surface area of the antenna can be as a result of being feathery.

Male Hawk-moths have antennae that are more like combs than feathers - again the surface area of the antenna is increased with this design so that the males have a better sense of smell.

The Emperor Moth is capable of picking up the scent of a female up to 5 kms away!