Firefly Lifecycle Project

Colorado Fireflies

Did you know that Colorado has native fireflies? Most people are unaware of this due to light pollution and development destroying their habitat. Learn about Butterfly Pavilion’s initiative to conserve these small yet mighty animals and how you can do your part!

As firefly populations decline at alarming rates, Butterfly Pavilion is working to understand how to rear and conserve native fireflies through its Firefly Lifecycle Project.

Fireflies—bioluminescent beetles found in small, localized wetland habitats across Colorado—play an important role in their ecosystems. They act as predators of invertebrates like snails and earthworms and serve as prey for birds, reptiles, and amphibians. Their presence is also an important indicator of healthy wetland environments.

However, firefly populations are under threat due to habitat loss, water pollution, and increasing light pollution. To better protect these species, Butterfly Pavilion researchers have been studying their lifecycle and environmental needs since 2017.

Research & Rearing Efforts

Each summer, researchers collect a small number of adult fireflies under permit from wild populations in Colorado. These adults are brought back to Butterfly Pavilion, where they are carefully bred and monitored in controlled conditions.

Their eggs develop into larvae, which are raised in specialized lab environments. Researchers closely manage factors like moisture, food, and habitat conditions to better understand what triggers development from larva to pupa and ultimately to adult fireflies.

This process is incredibly complex—breeding fireflies under human care has only rarely been accomplished in the United States and remains a major scientific challenge.

Key Milestones

• Fireflies can take 2–3 years to develop from egg to adult.
• Butterfly Pavilion successfully raised multiple adult fireflies from lab-reared larvae.
• Researchers achieved a major breakthrough by completing the full lifecycle—egg, larva, pupa, and adult—under human care.
• Lab-reared adults have successfully mated and produced viable offspring.

These milestones represent a critical step forward in understanding and conserving native firefly species in Colorado and beyond.

Why It Matters

Fireflies are more than just a magical part of summer nights—they are a key indicator species for wetland health. Their survival reflects the overall condition of ecosystems, including water quality and biodiversity.

By studying and successfully rearing fireflies, researchers can better understand their full life history and develop science-based conservation strategies. This work may eventually support restoring populations and protecting critical wetland habitats.

Butterfly Pavilion’s long-term goal is to establish sustainable, genetically diverse populations and contribute to large-scale restoration efforts, while also educating communities on how to protect firefly habitats—such as reducing light pollution and limiting pesticide use near wetlands.

Become a Community Scientist!

There is a lack of scientific research about fireflies, so we need your help! Become a community scientist and help Butterfly Pavilion track firefly populations around Colorado. Download and print out this datasheet and take it out into the field with you to collect sighting information.

Download Datasheet

Have you seen fireflies in Colorado? We want to know where! Submit your sighting below!

Submit Data

Public Locations for Firefly Viewing

Some parks are not open late enough for visitors to see fireflies during public hours, however, they may host guided walks to view fireflies after hours. Please respect the posted hours of all parks and check with them in advance.

• Riverbend Ponds Natural Area in Fort Collins, CO
  Open until 11 pm
  Fireflies flash along the boardwalk in the northeastern side of the natural area
  Fort Collins Natural Area volunteers lead guided firefly walks in June and July
• Morey Wildlife Reserve in Loveland, CO
  Open from dawn to dusk
  The City of Loveland hosts Fireflies in the Meadows walks in June and July
  Bicycles and dogs are prohibited
• Sawhill Ponds Open Space, Boulder, CO
  Open until 11 pm
  Fireflies have been spotted on the south side of the open space near the railroad tracks
• Fountain Creek Regional Park in Fountain, CO
  Open until 9 pm
  The Fountain Creek Nature Center offers firefly hikes in June and July
• Filoha Meadows Nature Preserve in Redstone, CO
  No access in the evenings
  Roaring Fork Conservancy leads guided firefly walks in July

Frequently Asked Questions

Firefly Facts

What are fireflies and why do they flash?

Fireflies are beetles in the family Lampyridae. Like other beetles, fireflies have six legs, two eyes, two antennae, a pair of wings, and a hard exoskeleton to protect their body. There are over 2,000 species of fireflies across the world. However, in Colorado fireflies exist in small populations dispersed throughout the state. Fireflies flash to find mates. Flashes are like a language for fireflies. Species have their own unique flashing patterns to recognize each other.

How do they flash?

Fireflies flash using bioluminescence. A chemical reaction takes place inside their light-producing organs. When oxygen is exposed to certain chemical compounds inside the organs, the reaction produces light. Not all fireflies flash as adults. There are three types of fireflies: flashing fireflies, diurnal fireflies, and glowworms. The diurnal (active during the day) fireflies do not flash as adults, though they may emit some light. Glowworms may flash or emit a constant glow. The fireflies that we refer to as “lightning bugs” are the nocturnal flashing fireflies.

What is their habitat?

Fireflies live near fresh water. They are often found near creeks, ponds, rivers, lakes, marshes, and even hot springs. They are commonly seen in forests, fields, and meadows near these sources of water. During the mating season, flashing females tend to wait on vegetation while the males fly, so wetland areas with low vegetation are popular.

What do they eat?

Larvae eat a variety of prey items, though some specifically eat soft bodied invertebrates such as earthworms, slugs, and snails. Some species don’t eat at all as adults, while others are predaceous. Females in the Photuris genus even mimic the flashing patterns of females in the Photinus genus to draw in males to eat them. Some adults consume nectar from plants and may act as pollinators.

How do they survive in winter?

Fireflies hatch from eggs in July through August then develop into larvae. The larvae are voracious predators and develop through multiple instars (stages of development). They protect themselves from freezing winter temperatures by sheltering in the ground or under tree bark.

Fireflies in Colorado

Which species are in Colorado?

We truly aren’t sure! A handful of species have been positively identified in Colorado; however, we lack scientific research about the exact species for many of the population. More research is needed to identify the firefly species in Colorado and their ranges.

Where can you see fireflies in Colorado?

Firefly sightings have been reported across the Front Range and in Western and Southeastern Colorado. Look for open spaces with wetlands. The flashing fireflies can be seen around late June through July when the nights in Colorado begin to warm up. They typically start flashing after 9:00pm.

Support

Why are fireflies important?

Fireflies are beloved for their unique light shows, but they also serve important ecological roles. They act as pest control for their prey species such as snails and slugs. They act as food for wildlife such as toads, frogs, newts, birds, and spiders. Some species which eat nectar and pollen may even act as pollinators.

How can we protect fireflies?

Fireflies are threatened by habitat loss, pesticide use and light pollution. You can protect firefly habitat by:

• Supporting land conservation and habitat restoration.
• Staying on designated paths when visiting natural areas to avoid damaging their habitat.
• Enjoying fireflies in the wild and not catching them.
• Turning off unnecessary lights near their habitats in June through August.

How can I get involved?

Become a community scientist and help Butterfly Pavilion track firefly populations around Colorado.