Where Did All The Bay State's Fireflies Go? Only In Massachusetts

Only In Massachusetts is an occasional series where Patch tries to find answers to questions about life in Massachusetts. Have a question about the Bay State that needs answering? Send it to dave.copeland@patch.com.

Of the more than 2,000 firefly species in the worldwide, at least 20 can be found in Massachusetts.

But good luck finding them.

Ask just about any lifelong Massachusetts who was a kid in the 1980s or earlier, and they'll tell you there are far fewer fireflies in the Bay State these days. They'll tell you about thousands of lightning bugs frolicking in suburban backyards in July and August. They'll tell you about the thrill of momentarily catching one in a glass jar, then freeing it back into the night.

No one knows for sure how many fireflies have been lost. Firefly Watch, a community science project, has been tracking firefly sightings in Massachusetts since 2008. But the program relies on volunteer amateurs who log sightings each week through the summer, and researchers say far more data is needed.

So science can't tell us how many fireflies remain in Massachusetts, but it can offer hints on why seeing them in 2021 is far harder than it was in 1981.

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Last year, Tufts University insect ecologist Sara Lewis surveyed firefly experts from around the world and asked what they thought were the biggest threats to lightning bugs. The top three reasons given in the survey: habitat loss, light pollution and increased use of pesticides.

The state's people population was 5.8 million in 1981. It's 6.9 million today. That's a lot more people taking up habitat, leaving the lights on and putting pesticides on the lawn outside their habitat. Water pollution, invasive species and climate change were also listed as threats in the survey; the first two are not as big of a problem in Massachusetts as they are in other parts of the world.

By the time you see a firefly floating around your backyard, it has spent two years living as larvae under your lawn and feasting on earthworms and other soft-bodied invertebrates. When the ground gets dug up to build a new condo complex, or you use pesticides and fertilizers on your lawn, the chances the fireflies make it past the larvae stage drop.

Light pollution also plays a huge role. When fireflies glow, they're trying to attract a mate. Light pollution makes it harder for those potential mates to find their match. More people in Massachusetts means more lights, and that prevents fireflies from getting in the mood for love.

"Trying to find mates against a background that's very, very bright — it's a lot harder to see those signals," Lewis, the author of the Tufts firefly study, told WBUR last year. "If you artificially increase the brightness at night, firefly males might continue to flash, but the females don't respond."

Female fireflies, in case you were wondering, prefer males who either signal with a series of quick flashes or with flashes that are slightly longer.

"The females are really inhibited from responding to males -- to continuing that courtship dialog — if there's a bright background," Lewis told the radio station.

Dave Copeland is Patch's regional editor for Massachusetts, New Hampshire and Rhode Island and can be reached at dave.copeland@patch.com or by calling 617-433-7851. Follow him on Twitter (@CopeWrites) and Facebook (/copewrites).