Colorado is home to fireflies, though they are often less commonly observed than in other parts of the country. Small populations of these bioluminescent beetles exist throughout the state, particularly in wetland habitats. While many people associate fireflies with abundant flashing lights, their presence in Colorado is often more elusive.
Firefly Varieties in Colorado
Fireflies are beetles belonging to the family Lampyridae, with over 2,000 species worldwide. In Colorado, researchers are still working to identify all specific species present, but several types have been confirmed. These include both flashing fireflies and “dark fireflies,” which do not produce light as adults.
One specific genus observed in Colorado is Pyractomena, alongside other fireflies like Photuris. Additionally, the state hosts at least one species of glowworm, which is a type of firefly where the adult females retain a larval appearance and glow, while the males resemble dark firefly adults.
Where and When to Spot Them
Fireflies generally favor moist, fresh environments like wetlands. They can be found in various open spaces with wetlands across the Front Range, as well as in Western and Southeastern Colorado.
The best time to look for flashing fireflies is during late June through July, during their mating season. They typically begin flashing after 9:00 PM. Specific public locations where fireflies have been sighted include Riverbend Ponds Natural Area in Fort Collins, Morey Wildlife Reserve in Loveland, and Sawhill Ponds Open Space in Boulder.
Why They Are Less Common
Fireflies are generally less common in Colorado compared to more humid regions. Colorado’s climate is considerably drier than the eastern United States. Fireflies require consistent moisture for their life cycle, from eggs laid in the soil to their larval and adult stages.
Elevation also plays a role, as fireflies tend to cluster in swampy areas and are active for only a few weeks per year, typically from mid-June to mid-July, even at higher altitudes like Divide. Furthermore, light pollution in populated areas can disrupt fireflies’ ability to communicate through their bioluminescent flashes, which are used for mating.
Firefly Varieties in Colorado
In Colorado, researchers are still working to identify all specific species present, but several types have been confirmed. These include both flashing fireflies and “dark fireflies,” which do not produce light as adults. At least five different bioluminescent species are thought to be present in the state.
One common non-luminescent variety identified is Pyropyga nigricans, which can be found in irrigated lawns. Among the luminescent species, the genus Photuris is common, with some populations in Colorado exhibiting unique flashing patterns. Another firefly genus identified in the state is Pyractomena. Additionally, Colorado is home to glowworms, such as Microphotus pecosenis, also known as mountain glow worms, where the adult females glow to attract males.
Where and When to Spot Them
Observing fireflies in Colorado requires knowing their preferred habitats and activity times. These insects generally favor moist, fresh environments, which explains their presence in wetlands. They are commonly found near creeks, ponds, rivers, lakes, and marshes.
The prime time to look for flashing fireflies is during late June through July, as this period aligns with their mating season. They typically begin their light displays after 9:00 PM, continuing into the night. Specific public locations where fireflies have been sighted include Riverbend Ponds Natural Area in Fort Collins, Morey Wildlife Reserve in Loveland, and Sawhill Ponds Open Space in Boulder. Other reports indicate sightings in areas ranging from Greeley to Pueblo along the Front Range, and in mountain valleys near Moffat, Divide, and Durango.
Why They Are Less Common
Fireflies are generally less common in Colorado compared to more humid regions due to several environmental factors. Colorado’s climate is considerably drier than the eastern United States, where fireflies are more widespread, and these insects require consistent moisture for their life cycle. This includes the development of eggs and larvae in moist soil.
Elevation also plays a role, as Colorado fireflies tend to cluster in specific swampy areas and are active for only a few weeks each year, appearing briefly from mid-June to mid-July. Furthermore, artificial light in populated areas can disrupt fireflies’ ability to communicate through their bioluminescent flashes, which are essential for attracting mates. This combination of dry climate, specific habitat requirements, and light pollution contributes to their perceived rarity in the state.