Once upon a time, the firefly love story was simple. A male firefly would float above a meadow, flashing a light signal to announce his presence to any females resting below. In the grass, an interested female of his species would signal back to him, telling him to come closer. The conversation would continue while the male made his way to her; when he reached her and the pair would mate. Throughout the brief courtship, each recognized the other as a potential mate by watching for the pattern of flashes that defined their species.
But then things got a bit more complicated. Females of the firefly genus Photuris like to eat other fireflies. Photuris females employ a clever strategy for hunting their prey – they mimic the flash patterns of other firefly species. A hungry female firefly will watch the sky above her, waiting for a Photinus or Pyractonema male to signal to a mate. She replies by mimicking a female of his species, tricking him into coming closer and closer. The successful femme fatale lures her prey to her, until it's too late for the naïve suitor and he becomes her next meal.
Don't feel bad for the males just yet. Photuris males have their own bag of bioluminescent tricks for fooling females. After females lay eggs, they usually hunt for a meal. Males looking for a mate take advantage of the hungry females by mimicking another species she hopes to eat. They're so adept at this mimicry, that they even change their flight altitude to match that of the other species. Throughout the evening, from dusk until dark, a male may change his flash pattern to copy the varying prey species that become active at different times of the night. She flashes her sneaky signal, trying to lure in a meal, and he returns an equally deceptive pattern, hoping to get close enough to mate with her.
The champion of aggressive mimicry, as this practice is called, is the species Photuris versicolor. The female can accurately mimic almost a dozen other prey species.