Butterfly Anatomy – The Head

Here's a brief overview of the structures found on a butterfly's head.

Eyes:
A butterfly’s compound eyes are made up of thousands of ommatidia, each of which senses light and images and provides the butterfly with a mosaic view of the world around them. Butterflies can see a nearly 360 degree radius without moving their heads.

Butterflies see in color and in ultra-violet light, making their view of the world very different from ours. For instance, they can detect patterns on a flower’s petals that human eyes cannot, allowing them to easily tell a yellow flower that is a good source of nectar from a different kind of yellow flower that is not. Learn much more about butterfly vision by clicking here.

Proboscis:
The proboscis is a straw-like tube that curls up when not in use. The butterfly can extend the proboscis deep into a flower to sip nectar. Butterflies also use the proboscis to drink water and juice from rotting fruits. Some species, like Zebra Longwings, also use their proboscis to collect pollen, from which they obtain extra sustenance.

The proboscis is actually two separate tube sections that "zip" together to form a continuous channel when a butterfly first emerges from chrysalis. You can see the connection in this microscope image of a butterfly proboscis.

Antennae:
Butterfly antennae are segmented and can be moved and positioned to help the butterfly sense their surroundings. Butterflies can use their antennae to detect pheremones, or scents that help butterflies locate mates. They also use them to test the chemical qualities of plants or soil. It is even conjectured that butterflies use their antennae for communication.

Johnston’s Organ:
At the base of the antennae is the Johnston’s Organ, which helps a butterfly maintain balance and orientation in flight. This organ senses the position of the antennae and detects how they may be affected by outside influences like wind. This allows the butterfly to make fine adjustments to its wings and maintain balance while flying.