This June 14, 2018 photo shows Peggy Butler, organizer of the Pennsylvania Firefly Festival looking at some fireflies in a jar during an evening hike overlooking the Tionesta Creek and Firefly Island, left rear, in Kettleville, Pa. For several weeks in June each year people from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press
KELLETTVILLE, Pa. (AP) - Every year in North America as spring turns to summer, fireflies emerge in parks, forests and backyards.
But one type of firefly has a unique capability. They blink in unison and are called synchronous (SING-kruh-ness) fireflies.
They're found in a few places like the Smoky Mountains in Tennessee and the Allegheny National Forest in Pennsylvania.
Their rhythmic displays are magical to observe. They've become a tourist attraction in some places, with festivals and late-night tours.
Scientists know that male fireflies light up to attract females. But they're not sure why these fireflies light up in unison. Some suggest that it's to the fireflies' advantage to cluster and show off their lights in a synchronized display in order to better attract attention from the females.
This June 14, 2018 photo shows Peggy Butler, organizer of the Pennsylvania Firefly Festival, as night falls over her Black Caddis Ranch on the edge of the Allegheny Forest, heading out in search of fireflies in Kelletville, Pa. For several weeks in June each year people from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press
This June 13, 2018 shows versicolor, or "Chinese lanterns," fireflies that seem to float through the air along a path on the Tionesta Creek in Kettleville, Pa. For several weeks in June each year people from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press
This June 13, 2018 photo shows a sign in the Allegheny National Forest that directs hikers to Peggy and Ken Butler's Black Caddis Ranch in Kelletville, Pa. For several weeks in June each year people from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press
In this June 14, 2018 photo Peggy Butler, organizer of the Pennsylvania Firefly Festival, checks her firefly net while preparing for an after dark hike in search of fireflies on and near Black Caddis Ranch on the edge of the Allegheny Forest, in Kelletville, Pa. For several weeks in June folks from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press
This June 14, 2018 photo shows Peggy Butler, organizer of the Pennsylvania Firefly Festival, at her Black Caddis Ranch, as she prepares for an after-dark hike along the nearby Tionesta Creek to Firefly Island in search of fireflies in Kelletville, Pa. For several weeks in June folks from around the world make the trek to this northwest Pennsylvania forest to see all manner of fireflies. (AP Photo/Gene J. Puskar)
The Associated Press