These Fireflies Flirt With Heart Shaped Lights

Each species of flashing firefly has a secret code to attract their mates – these ones do so with a light-up heart.

Earlier this year I wrote about a femme fatale species of firefly, a trickster vixen from the genus Photuris that lures males of other firefly groups to their gruesome demise. I know everything is fair when it comes to survival, but the deceit is nonetheless remarkable!

However, hidden in that story was a small detail that I haven’t stopped thinking about: Female fireflies from another species, Photinus pyralis, make their bids for love (well, mating at least) with a heart-shaped light.

heart shape firefly

Like Mother Nature’s own flashing emoji, when she spies the special signal from a fellow-species fella, she twists her abdomen in his direction and reveals her secret heart. If only it were so easy for us humans.

The male of the species, known as the common eastern firefly or big dipper, is no slouch in the seduction department, either. He gets her attention by tracing out an acrobatic “J” in the sky … he does it in a big graceful dipping motion, hence the name.


And where does all this flirty flashing lead?

Firefly light is biochemical. The complex folds inside their abdominal lanterns contain two types of chemicals, luciferases and luciferins, which interact in the presence of oxygen to produce the light.

But fireflies like the Big Dippers do much more with chemistry than just make light. They can mix together an array of other compounds, including invisible pheromones for mating, and others called lucibufagins (“loosa-BOOF-ajins”) that ward off predators like spiders and birds.

Males pass some of these chemicals, including the highly potent lucibufagins, to females during the mating process. That so-called nuptial gift plays a role in the reproductive success of both partners.

And eventually baby fireflies … complete with big dips and heart-shaped lanterns so that a new generation of fireflies can light up the nighttime sky with their special language of love.

The adult females, which resemble armored, rose-colored worms, are the only ones that light up. The males fly, but don’t glow at all. Nonetheless, their mating habits follow the firefly pattern, with males on the wing searching for females hidden in the dark.