ITHACA, N.Y. -- The characteristic flashes that summon male fireflies of the genus Photinus could come from female Photinus fireflies. But just as likely, Cornell University chemical ecologists have discovered, the signaling females are of a different genus, Photuris, and they're not especially interested in courtship.
Rather, the femmes fatales fireflies are luring males close enough to eat them. The males contain defensive chemicals that females need to repel predators, such as spiders. Mimicry and murder provide a lifesaving meal, the Cornell researchers report in the Proceedings of the National Academy of Sciences (Sept. 2, 1997, Vol. 94, pp. 9723-9728).
Defensive chemicals called lucibufagins, which Photinus fireflies have and Photuris fireflies want, are exuded in firefly blood.
"But they're hardly bleeding hearts," said Thomas Eisner, Cornell's Schurman Professor of Chemical Ecology and leader of the investigation into firefly fatal attraction. "This is 'reflex bleeding' that commonly occurs when fireflies are disturbed." Tiny droplets of blood from Photinus fireflies -- and from Photuris fireflies that eat them -- contain enough lucibufagin to keep chemically endowed fireflies from being eaten by certain spiders, birds and probably other predatory animals, Eisner said.
Conducting and reporting the study along with Eisner, who is a member of the National Academy of Sciences, were Michael A. Goetz, a postdoctoral fellow in chemistry at the time of the research; David E. Hill, postdoctoral fellow in neurobiology and behavior at the time; Scott R. Smedley, postdoctoral fellow in neurobiology and behavior; and Jerrold Meinwald, the Goldwin Smith Professor of Chemistry at Cornell and also a member of the National Academy of Sciences.
The study employed adult fireflies (which entomologists regard as beetles, not true flies) from the Ithaca, N.Y., area, as well as larval fireflies from Montgomery County in Maryland and Alachua County
Contact: Roger Segelken
Cornell University News Service