Fireflies in Colorado: Where, when to see the bioluminescence beauties

Fireflies in Colorado?

Aren't they a Midwest thing?

Not only does Colorado have fireflies but the state also boasts an emerging program that is breeding these bioluminescence beauties of the beetle world.

And, yes, there is even a World Firefly Day — July 2 — to honor these iconic insects that have mesmerized many while playing in backyards.

"Fireflies are so magical; they capture people's hearts,'' Cori Brant, entomology manager at the Butterfly Pavilion, told the Coloradoan on Monday. "They remind people of mythology and fairies. Seeing them in backyards is nostalgic. They are charismatic and the silliest looking things, with big eyes, but are so cute.''

Butterfly Pavilion's groundbreaking work and how Fort Collins has played a major role

Conservation organizations have raised endangered animals such as rhinos and condors in captivity to help wild populations.

Since 2017, the Butterfly Pavilion’s groundbreaking Firefly Life Cycle Project has done similar work with much smaller creatures: fireflies.

On June 11, the fourth firefly captured in the wild in Fort Collins and bred at the Denver facility's lab pupated from larvae to adult. It was named Ferdinand.

This is no easy task given the complexity of nurturing eggs to adulthood. Researchers spent four years meticulously tinkering with the right conditions to trigger larvae to pupate.

The Butterfly Pavilion believes it is the first to have successfully reared males and females of a Colorado species of firefly from eggs to adulthood.

"The amount of care to perfect raising fireflies was a learning experience,'' Brant said. "It's the composition of the soil, special food mixture, humidity and temperature. But we did it to help zoos, aquariums and others to restore fireflies in the wild.''

So much still needs to be learned about fireflies in Colorado, including how many species live in the state, Brant said.

"We have about 14 species we are looking at, but new ones are found every year,'' she said.

Firefly capture can be as complicated as breeding the beetles

Butterfly Pavilion researchers over the past several years have traveled to Fort Collins one night a year to collect wild adult fireflies under a research permit.

Last month, they visited the city-managed Riverbend Ponds Natural Area off East Prospect Road to capture fireflies. Brant said fireflies are found around water sources such as marshes, river and streams.

Their permit allowed for the take of 10 females and 40 males, which they caught by hand, placed them in a catch cup to determine gender, then placed them in enclosures to take to the pavilion lab.

Brant said determining the sex of fireflies can be difficult.

"When looking at the abdomens, female glow organs won't fill the entire space, like males, but sometimes they do,'' she explained. "Males have very large eyes but that is not the best way to determine sex. It's just as complicated as it sounds.''

She said when walking through fields near water sources, firefly males usually patrol above the grass and females tend to stay in the grass.

Males fly above the grass and emit a particular flash pattern to gain the attention of a female. Females lie in wait in the grass. If a female is interested in the male, she will respond by flashing back, Brant said.

"There are very specific light patterns for each species,'' she said. "When she signals, 'yes, you are the male I want,' they end up mating.''

If everything goes well back in the pavilion lab, about two years later a new generation of fireflies will emerge, furthering the critical work that fireflies provide as canaries in the coal mine for water quality.

"A decline in fireflies is an indicator of environmental decline,'' Brant said. "Destruction of habitat, pollution, climate change all have an impact on fireflies.''

More: Meet Mr. FireflyYes, Colorado has fireflies and they are big, bad, bright and native

When and where to see fireflies in Colorado

Fireflies usually start flashing after 9 p.m. in Colorado from around late June through July. Look for open spaces with wetlands.

Here are public places to find them in the Fort Collins/Loveland area:

• Riverbend Ponds Natural Area: 2856 E. Prospect Road, Fort Collins. Open until 11 p.m. Fireflies flash along the boardwalk on the northeastern side of the natural area. Find more information here.
• Morey Wildlife Reserve: 5439 Cedar Valley Drive, Loveland. Open until 10 p.m. 33-acre natural area along the Big Thompson River just west of Mariana Butte Golf Course offers restored wetlands, river habitat and open fields. Find more information here.

Find more firefly viewing areas around the state here.