Those Flashy Males

Among fireflies, flashier males get the girls

• Laura Tangley
• Aug 01, 2003

EVER WONDER what a male firefly is saying to a female when it flashes its light? According to a new study, he's trying to tell her he'll be a good provider.

Scientists have long known that flash patterns vary from one firefly species to another, and that a female uses these unique patterns to ensure she mates with a male of her own kind. But it turns out that the frequency and duration of light flashes also vary within species. Using computer-generated lights, Tufts University biologists tested which flash patterns attracted the most females. They found that the females responded best to longer flashes.

Following a hunch, the scientists then tested whether a longer flash might be correlated with a larger spermatphore, the high-protein nutritional gift a male firefly gives a female after mating, which she uses to feed her eggs. They discovered that the males with longer flashes did indeed give bigger gifts. According to coauthor Christopher Cratsley, "Males have only about 10 opportunities to mate, so they need to stand out in the frenzied crowd of competitors and communicate to females that they're worthy of consideration."