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Health & Science

Ideal Conditions Lead to Summer Firefly Boom

photo of firefly
While the number of fireflies is surging in certain regions, overall populations around the world are declining.

If you’ve noticed more fireflies lighting up your backyard, you’re not alone.

Whether you call it a lightning bug or a firefly, or perhaps by its scientific name, Lampyridae, chances are you’ve had some experience with the tiny flying insect that flashes and blinks its way through summer evenings.

And as Sara Lewis notes, astute watchers are noticing even more fireflies this summer than previous years.

“A lot of people are enjoying it, and I’m thrilled that people are enjoying it. And as firefly scientists we’re just trying to understand it,” said Lewis, an evolutionary biologist at Tufts University in Boston.

She also wrote the book "Silent Sparks: the Wondrous Life Fireflies."

She said the first thing you have to know about fireflies is that they live underground for two years, as eggs and then juveniles. And they love wet conditions, like those in the spring of 2017.

“Those were great conditions for baby fireflies, called larvae, because they live underground, and they feed on earthworms and snails and slugs, "Lewis said. "And so those wet conditions mean that more larvae are surviving to eventually into emerge into adults."

But she also explained that despite the surge in population in certain regions this summer, fireflies around the world are in decline. One of the greatest threats is light pollution.

“You know that fireflies use bioluminescent signals to find and attract their mates," she said. "And when there is a lot of artificial light it’s harder for them to see each other’s signals. It's harder for them to find mates.” 

Some species of fireflies are also victims of habitat loss because of development and climate change.