A study recently brought up an astonishing hypothesis. Several species of fireflies generate ultrasonic clicks by simply moving their wings. According to scientists, this is intended to protect against certain predators such as bats.
Flee predators with sound
There are over 2,000 species of fireflies in the world. In 2020, an international study estimated that all of these species are endangered. They face a loss of their habitat, the increase in pesticides and fertilizers that are used in agriculture, or even light pollution. Fireflies are known for their ability to emit light. These are signals essential in communication of these insects, moreover emitted by bioluminescence. Most of the time, these signals are used to attract their romantic partner. However, they could also have a whole other use.
According to a study published by iScience on February 15, 2021, it would also be a question of warding off predators. However, the effectiveness of this kind of light on predators would not be very effective. Researchers at Tel Aviv University (Israel) say they have discovered a second type of signal: some kind of sound armor. The goal is to more easily escape flying mammals such as bats.
Clicks for bats
Originally, researchers were working on the echolocation of bats. With their microphones, they have picked up unusual sounds at frequencies similar to the sounds of bats, except that these came from fireflies. Scientists therefore decided to conduct the investigation by studying three species of the genera Curtos, Luciola and Sclerotia (Vietnam) and one of its kind Lampyroid (Israel). However, all these species emit ultrasonic clicks, the frequency of which is between 20 and 130 kHz.
According to the study leaders, clicks have a rhythm similar to that of the wings of fireflies. It is therefore quite possible that these same wings produce them. Furthermore, the frequencies measured do not correspond to what fireflies are able to hear. So these clicks are intended for other animals like bats. However, it turns out that the frequencies correspond to a range that most of these mammals can hear.
For researchers, this ability of fireflies is similar to that of some moths. These signal their harmfulness by ultrasonic clicks. This is about aposematic signals, in other words warning signs. The next step for scientists will be to try to understand the potential effects of these clicks on predators.