Some female fireflies lure males of another species with promises of sex but eat them instead to obtain a chemical that deters predators, said a Cornell University study released Monday.
The females of the species Photuris versicolor imitate the light signals with which females of the species Photinus ignitus respond to courtship by their own males, it said.Some of the males, which contain useful chemicals known as lucibufagins, fall for it and end up dead. "Mimicry and murder provide a lifesaving meal," said the Cornell researchers.
The scientists found that when disturbed, the Photinus fireflies, and the Photuris flies that eat them, exude enough lucibufagin in their blood to deter spiders, birds and probably other predatory animals.
"This strategy - acquiring ready-made defensive chemicals from other organisms - turns out to be quite common in nature, said Thomas Eisner, Schurman professor of chemical ecology at the university in Ithaca, New York.
"The more we study insects, the more we find them taking chemical defenses from plants and from other insects."
The study, based on fireflies in New York state, Maryland and Florida, appears in Tuesday's Proceedings of the National Academy of Sciences.