How To See Fireflies

Closeup – Terry Priest

The heavy air cools off slowly while a thunderstorm recedes into the distance. The first stars appear in the blue twilight sky. A green light blinks on the ground before taking flight and appearing in a different place. More and more appear, flashing above and all around you. Some are predictable and some not. Chasing fireflies on a warm summer night is one of those childhood memories that stays with you. They are one of the most beloved insects. And just like astronomers, they prefer dark sites.


Fireflies, or Lampyridae, are a type of beetle with more than 2,000 known species. There are some that do not fly, and some that do not glow. Through a chemical reaction called bioluminescence, they produce light on their abdomen as a way to attract a mate. During their larval stage they are called glowworms. Typically the males flash in flight every 5 seconds and the females flash every 2 seconds while stationary. The first blinks of light during twilight tend to be more yellow in color. As it gets darker they become more green. A rare species called synchronous fireflies lights up simultaneously, unlike most others which are random. Great Smoky Mountains National Park and Congaree National Park are two places where synchronous fireflies are found. In parts of the world they are also called lightning bugs.


In general stargazing is better in a dry climate. But fireflies on the other hand prefer a humid climate. There are a wide range of environments that host fireflies, but access to moisture is critical. Damp meadows, forests, irrigated lawns, marshes, and agricultural fields are some ideal habitats as long as they’re dark enough. Even though I’m partial to the western US, fireflies are one of the things I miss most about the Midwest.

Fireflies are found on every continent except Antarctica. In Asia some of the hotspots include Thailand, Malaysia, Philippines, Taiwan, India, and Japan. In Europe they are mainly found in the south. Firefly tours are popular in parts of Mexico. In the United States, they are most prevalent east of the Mississippi River. Pennsylvania, Tennessee, South Carolina, and Florida are all great spots. Small populations do exist in the Western US, but they are rare. Here is a map of firefly tourism hotspots in the US.

Austria – Bernd Thaller

Time of Year

In higher latitudes, fireflies are mainly a summer phenomena, appearing as early as late May and fading away after July. At lower mid latitudes, fireflies appear in the spring months from March through May. Closer to the Equator, fireflies may be present year round.

The weather plays a big part in when they appear. Years that are wetter and warmer may lead them to emerge earlier than normal. But cool weather and droughts will reduce their numbers. Once temperatures drop into the 50’s firefly activity is minimal. Stormy and windy weather makes it difficult for them to fly. But right before or right after a storm can be the best time to watch for fireflies.

Firefly over Lake Sugema, Iowa

Habitat Loss

Fireflies are not as plentiful as they once were and light pollution is to blame. Artificial lighting disrupts their ability to signal to each other. Worsening water quality from pesticides and other pollutants also leads to their decline. Increasing development reduces their habitat. A changing climate and precipitation patterns move them to different areas. Not all of the reasons for firefly decline are fully known. But you can help gather more information by reporting your sightings to scientists.

Weinberg King State Park, Illinois

Attracting Fireflies

There are steps you can take to help fireflies return to your yard.

  • Reduce outdoor lighting. Turning off unnecessary lights or shielding them has many benefits.
  • Avoid using pesticides. These will runoff and hurt nearby water quality.
  • Keep grass longer. Mowing less often and not as short is more firefly-friendly.
  • Plant shrubs and trees that are native to your area
  • Instead of raking up all leaves, keep some woody debris and leaf litter on the edges of your property
  • More tips here: How to Build Firefly Habitat
Taiwan forest – Fred Huang


Fireflies aren’t just fun to watch, but also to photograph. With a single image you may not capture much. But by using a very long exposure or stacking multiple images, you can get dozens or hundreds of little green lights. They tend to stand out more against a dark background, like a grove of trees. If you want more detail in the foreground, try taking pictures before it’s fully dark or during a moonlit night. If the stars are part of your composition, then you’ll want to set your focus to infinity. If in a forest, then the focus should be set much closer. Some fireflies will likely be out of focus depending on the distance to the camera. But this isn’t necessarily a bad thing, as long as some trails are sharp.

The choice of lens depends on how many fireflies there are. If there are a lot, go wide. Otherwise if they are hanging out in a small area, a tighter framing like 50mm would be better. Some settings to start with might be 10 seconds, f/2.8, ISO6400. Then adjust as needed depending on the light level. If you set your camera to capture a couple hundred images, then you also have the option of turning it into a time lapse video. The easiest way to stack them is with a program like StarStax. More advanced editing techniques might include overlaying a single image of the stars to replace the startrails, which is what I did below.

Rare fireflies in Eastern Montana during a wet summer

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