How do insects smell?

With antennae. The antennae of May beetles, for example, have 40,000 tiny pits. Each one is like a little nose for smelling. We wonder: If they catch cold, do they have 40,000 runny noses? Many insects give off special chemicals that only other insects can sense. Antennae let each kind of insect find food, tell friend from foe, and spot danger. Some male moths can find female moths that are up to 7 miles (11.2 km) away—just by their smell!