How and why do fireflies light up?
Fireflies in a jar. Photo by jamelah
Watching fireflies is my favorite thing about summer evenings.
Fireflies contain an organic compound in their abdomens, called luciferin. As air rushes into the abdomen, it reacts with the luciferin – it’s this chemical reaction that makes a firefly’s light. This kind of light is sometimes called a “cold light” because it generates so little heat.
The firefly can regulate the airflow into the abdomen to create a pulsating pattern. Fireflies flash in patterns that are recognizable to other fireflies.
Male fireflies light up to signal their desire for mates – and willing females attract the males with flashes of their own. But not all the flashing of fireflies is motivated by romance. While each firefly species has its own pattern of flashing, some females imitate the patterns of other species. Males land next to them – only to be eaten alive.
Some experts think the firefly’s flash may warn predators of the insect’s bitter taste. On the other hand, some frogs don’t seem to mind. They eat so many fireflies that they themselves begin to glow.
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