PROVIDENCE — On humid summer nights, sometimes it’s the gleam of fireflies, not city lights, that illuminates Roger Williams Park.

Providence Parks Department deputy superintendent Brian Byrnes said he’s started to see the beetles — yes, fireflies are actually beetles not flies — where he’s never seen them before. It’s just one sign, he said during a recent interview with ecoRI News, of the park’s increasing health.

Byrnes said there’s also a bald eagle making its home in the park and a growing fish population in the park’s ponds.

Byrnes and Parks Department superintendent Wendy Nilsson said the return of wildlife coincides with initiatives focused on improving water quality, managing stormwater, and maintaining more natural vegetation.

In particular, Nilsson said the park doesn’t use pesticides, has low- and no-mow zones, and mulches leaves in place “to create better protection for wildlife and smaller creatures and pollinators.”

David Gregg, executive director of the Rhode Island Natural History Survey, a clearinghouse for all things wildlife in the Ocean State, said all those measures would make Roger Williams Park a friendlier habitat for fireflies.

Firefly larvae live on the ground, in the dust, dead grass, and leaf litter, while the adults thrive among tall, wet meadows, in “lush green grass,” Gregg said.

“They don’t like mowed grass or flower beds with mulch,” he said. “They don’t do dry very well.”

They need areas that can retain moisture, something natural landscapes do well.

“Rewilding your lawn then is probably the right track for fireflies,” Gregg said.

He noted that although he isn’t particularly a firefly expert, he’d guess there are probably a few dozen kinds that can be found in Rhode Island.

Fireflies, also known as lightning bugs, “should be common,” Gregg added, “unless [the environment has] been messed up.”

On iNaturalist, a platform where amateurs and experts record and decipher wildlife observations, black fireflies, little gray fireflies, and winter fireflies, which actually don’t light up, have all been identified in and around Roger Williams Park.

Fireflies come in many different varieties that vary by habitat. “The fun thing about fireflies is that the adults can look very similar, but they flash in different ways, and that’s how they tell them apart,” Gregg said.

He noted it’s probably hard to catalog fireflies in the field because an observer would need to see the flash pattern before capturing them.

“It’s ripe for someone to get into,” he said.