The Senses of Butterflies: Hearing

Some butterfly families have a specialized organ on their wings that works somewhat like an ear. This organ is a fluid filled sac covered with a thin membrane. High frequency sounds will cause the membrane to vibrate and send signals to the butterfly’s brain.

Some butterflies are even able to differentiate between high and low pitch sounds which may help them with locating other members of their species or to avoid predators. The wide veins at the base of the fore wings contain nerve cells similar to those found in the hearing organs. Some species have good enough hearing abilities that they will react to the crunch of leaves under your feet as you approach them or will take flight in response to the click of a camera shutter.

The first butterfly ear structures were discovered in 1912 but it is only in recent years that scientists have begun to study the physiology of these organs. The ear structure on a butterfly wing is known as a Vogel's organ. This structure is made up of a thin tympanum bordered by a ring of rigid chitin and the inner surface of the tympanum has several sensory organs.

Hamadryas: The genus Hamadryas, also known as Cracker Butterflies, are known to emit clicking sounds when they are disturbed. The Blue Cracker (Hamadryas feronia) of Venezuela emits shorts trains of clicks and also double click sounds.

Morphos: Research at the University of Bristol in England has focused on the study of wing ears of the Blue Morpho (Morpho peleides) butterfly. Scientists used a tiny laser beam to scan the surface of the tympanal membrane of the wing ear and determined that different areas of the membrane vibrated with different frequency sounds. Lower frequency sounds vibrated only an area on the outer membrane  while higher frequency sounds could vibrate the entire membrane. This means that not only can the butterflies hear sound, but they are likely able to distinguish between different sounds.

Heliconians: In 2004, a UF researcher named Mirian Hay-Roe noticed that the Blue & White Longwing (Heliconius cydno) butterflies that she was studying were making clicking noises. Observation showed that the butterflies made clicking sounds when chasing rivals out of their territory, encountering members of their own species, flying with members of their own species and also while roosting at night. Mirian Hay Roe recoded the clicking sounds of this species and recordings of the noise are available here.

Hedyloids: This superfamily of nocturnal butterflies is often known as the American moth-butterflies. This group of butterflies has been found to possess a Vogel’s organ on their wings that may help them detect and avoid bats, a predator of these nocturnal butterflies.