KELLETTVILLE, Pa. (AP) — Picture a moonless June evening, shortly after midnight, deep in a northwestern Pennsylvania forest. Wild sounds echo gently. Stars glow far above through the canopy of trees. Otherwise it is dark — so very dark.
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 in a rhythmic display that lights up the night.