Photinus pyralis
In 3 days ~20% in a week ~40%
Photinus pyralis, also known by the common names the common eastern firefly or big dipper firefly, and sometimes called a "lightning bug", is a species of flying beetle. An organ on its abdomen is responsible for its light production. It is the most common species of firefly in North America and is typically found east of the Rocky Mountains. Photinus fireflies are often confused with fireflies of the similar-sounding genus, Photuris, which are also found in North America.
These fireflies are most noticeable around twilight in the spring and summer months. The common name, big dipper firefly, is due to the characteristic flight of the males, whose trajectory appears to follow a J-shape, lighting on the upswing. During flight, this J-pattern is used alongside light flashing to attract females, who rest on vegetation and signal back to males if interested. The firefly flashes are stimulated by light-activated proteins, not rhythmic impulses as originally thought.
Common Eastern fireflies are small soft-bodied beetles that are 9–19 mm (0.4–0.7 in) long. They have flat black or brown bodies with wing coverings, or elytra, that extend the length of their entire thorax... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Great Smoky Mountains National Park | 🇺🇸 United States | |
| 2 | Shenandoah National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Detroit | 🇺🇸 United States | |
| 2 | New York City | 🇺🇸 United States | |
| 3 | Baltimore | 🇺🇸 United States | |
| 4 | Philadelphia | 🇺🇸 United States | |
| 5 | Washington | 🇺🇸 United States | |
| 6 | Chicago | 🇺🇸 United States | |
| 7 | Dallas | 🇺🇸 United States | |
| 8 | Austin | 🇺🇸 United States | |
| 9 | San Antonio | 🇺🇸 United States | |
| 10 | Minneapolis [Saint Paul] | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Common Eastern Firefly sighting in Shenandoah National Park on a given day, based on 19 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 220th most-seen of the 723 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June to August
In those months about 10% of wildlife watchers report a Common Eastern Firefly in Shenandoah National Park on a given day, against under 5% in September to May, the lowest months.
Between 6 and 9 pm
Across all the parks we cover, that three-hour window holds the most Common Eastern Firefly sightings with a recorded time, and about half of them come between 6 pm and 6 am: it is seen both by day and at night.
Among the best
Of the 2 parks where we can rate Common Eastern Firefly sightings, Shenandoah National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Great Smoky Mountains National Park (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Common Eastern Firefly is recorded against all the insects logged in Shenandoah National Park (19 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
