It’s not unusual to see fireflies flashing in backyards here and there this time of year. But deep in a Pennsylvania forest, synchronous fireflies blink in unison, a rhythmic display that lights up the night. In this episode of the Associated Press Travel podcast “Get Outta Here,” AP Travel editor Beth Harpaz invites her colleague Ted Anthony to describe his visit to the Allegheny National Forest, where he observed this magical phenomenon. Anthony, who is AP’s director of digital innovation, explains what we do and don’t know about how and why the fireflies engage in this behavior, and also offers advice on planning a trip to see it.