The Purposes of Butterfly Antennae

Butterflies don't have noses, but they have smell receptors on their antennae and legs. These allow butterflies to sense flowers that are full of tasty nectar so they don't waste time landing on flowers that are empty of nourishment. The antennae smell receptors also sense the pheromones of other butterflies, helping them find mates when the time is right.

Butterflies tend to be active during the day, resting when night falls. Instead of just using their eyes to distinguish day from night, butterflies use their antennae as light receptors. The antennae track the position of the sun and turn that information into a time of day. When butterflies lose their antennae, they aren't able to determine time as well as those with intact antennae, butterfly researcher Dr. Steven Reppert told BBC News.

Another key element of butterfly antennae is their ability to help the butterflies fly in the right direction. This is especially important in butterflies who migrate, such as monarch butterflies. These groups must know which direction to fly during what season, such as flying south for the winter. This tends to work in conjunction with the clock feature; to keep flying south, for example, the antennae must determine what time it is and where the butterflies must be positioned relative to the sun's position in the sky. This navigation system also helps butterflies find their way back to favorite feeding grounds.

The antennae can sense the direction of the wind and changes in that direction, helping a butterfly ride the wind currents without losing its way or becoming disoriented. At the base of the antennae, butterflies have a special organ -- the Johnston's organ -- that draws information from the antennae to help keep the butterflies balanced. This organ helps butterflies find mates as well, recognizing the wing beats of other butterflies of the same species.