On summer nights, there are often fireflies flashing in the sky. There is a children’s song “Fireflies, hang lanterns, fly to the west to fly to the east, fly to the door of the house at night, and the baby will come home to send it.” However, the fireflies glow at night, not for lighting, but for courtship. Recently, researchers discovered that the glow of fireflies also warns bats not to eat them.
Such warnings are good for both fireflies and bats, because the smell of fireflies is very disgusting: when swallowed, the fireflies release a disgusting chemical that allows predators to spit them out.
The researchers put 8 bats in a dark room with 30 fireflies, plus three times the number of other insects (including beetles and moths). This lasted for 4 days. On the first night, all bats caught at least one firefly. But by the fourth night, most bats have learned to avoid fireflies and instead catch other insects.
For a long time, people believed that fireflies glow mainly to attract mating, but it seems that they also serve as a warning to bats. This new discovery also explains why firefly larvae glow when they are sexually immature.