A few firefly species flash in near-unison, making whole hillsides blink together. Photographing them is a lesson in patience, low light and respect for a fragile event.
Where and when
- Great Smoky Mountains National Park (Elkmont area, Tennessee): Photinus carolinus displays for about two weeks between late May and mid-June. Access is managed with a lottery for vehicle passes through Recreation.gov.
- Congaree National Park (South Carolina): synchronous Photuris frontalis fireflies, typically mid-May to early June.
- Allegheny National Forest (Pennsylvania) also hosts synchronous displays in early summer.
Timing varies with spring temperatures; parks announce dates each year.
Rules that matter
- No flash, no bright lights. Cover headlamps with red film and point them at the ground; light disrupts flashing.
- Stay on trails — female fireflies sit on the ground and in low vegetation.
- No bug spray dispersal near displays if asked, and no collecting.
Settings
- Tripod, wide fast lens (14–35 mm, f/1.4–f/2.8).
- ISO 1600–3200, 15–30 second exposures.
- Focus in twilight on a tree or a distant light, then switch to manual.
- Shoot continuously with an intervalometer for 20–40 minutes.
Stacking
Each frame captures a few flashes. Lighten-blend many frames to build a sky-like field of light in the forest — the same technique as star trails. The in-browser stacker works for this. Shoot one frame in late twilight for a clean forest background.
About 1 min read · Updated 2026-10-20