Some Firefly Species Await a Night That Never Comes
A study found that while some fireflies shrugged off light pollution, members of other species failed to mate even when males and females could find each other. From a report: As dusk deepens the shadow at the forest's edge, a tiny beacon lights up the gloom. Soon, the twilight is full of drifting lights, each winking a message in peculiar semaphore: "Male seeks female for brief union." This courtship plays out on summer nights the world over among beetles of the Lampyridae family, commonly known as fireflies. The darkness in which fireflies have always pursued their liaisons, however, has been breached by the glare of artificial lights. Humans' love affair with illumination has led to much of the Earth's habitable surfaces suffering light pollution at night. In recent years, scientists who study fireflies have heard from people who are worried that the insects may be in decline, said Avalon Owens, an entomologist at Tufts University. "There's this sense of doom. They seem to not be in places where they used to be," she said. So little is known about how fireflies live that it is hard to assess whether they are in danger -- and if so, why, said Dr. Owens. But in a study published Wednesday in the journal Royal Society Open Science, she and Sara Lewis, a professor of biology at Tufts University, shone some light on how fireflies respond to artificial illumination. Experiments in forests and fields as well as the lab showed that while some North American fireflies would mate with wild abandon, regardless of illumination, others did not complete a single successful mating under the glare of the lights. Fireflies seem to rely primarily on flashes of light to find each other, which means light pollution could threaten their ability to see mates. In the four common species the study examines, the females hide on the ground and observe as males wander the skies. When a female responds to a male's flashing with her own, the two enter into a dialogue that can end in a meeting, and eventually mating.
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