INDIANAPOLIS -- The yellow-green streaks of fireflies that bring a magical air to summer nights, inspire camp songs and often end up in jars in children's bedrooms may be flickering out in U.S. back yards as suburban sprawl encroaches on their habitats.
Scientists concerned by reports from the public that people are seeing fewer fireflies each summer have turned to a network of backyard volunteers to track their range and numbers.
Since the online Firefly Watch debuted in May 2008, about 5,100 people from 42 states have entered firefly data they collected in their yards, local parks and meadows, said Paul Fontaine, the Boston Museum of Science's vice president of education.
He said the museum is committed to operating the program and database for at least 10 years to provide a year-to-year snapshot of firefly distribution.
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The program, which also has volunteers in Canada, Costa Rica, Ghana and India, asks participants to watch fireflies for at least 10 minutes each week. Scientists at Massachusetts' Fitchburg State University and Tufts University are helping with the project.
The data accumulating in the Firefly Watch database may help determine whether fireflies' numbers are declining and, if so, where and why, said Christopher Cratsley, a Fitchburg biology professor who studies fireflies.
The beetles spend most of their life in rich, moist soils dining on earthworms and other soil dwellers as larva often called glow worms because their abdomens also flash.
Cratsley said replacing meadows and fields with strip malls and parking lots clearly cuts firefly numbers. And there's evidence that the glare of streetlights may interfere with the courtship of some species by washing out their flashes.
He said that pesticides, fertilizers and other chemicals can also kill the creatures that firefly larvae feed on but that the extent of that impact is unclear.
Far from development, Firefly Watch observer Steve Irvine still enjoys dazzling firefly displays.
Irvine, 57, has lived for more than three decades in a rural area of Ontario. It's a feast for firefly lovers. Just after dusk, summertime visitors can be surrounded by tens of thousands of fireflies.
"The fields around here are just alive with sparking light -- it's just magic," Irvine said. "There's countless thousands of them."