The Colorado June air was thick with summer heat. Mosquitoes rose in clouds around us, testing our resolve while we gathered our cameras and sensors. We walked into the wetland, down the unmarked path until the cattails rose shoulder-high. The sounds of frogs and crickets filled the air as we set up our cameras and waited. Then we spotted them: tiny lights lifting from the grasses, blinking in slow rhythms.
Bioluminescent lampyrid beetles, commonly known as fireflies or lightning bugs, are widespread throughout the Eastern United States but far more scarce west of Kansas.
Even though many are stargazers and hikers, most Colorado residents don’t know that fireflies share their state.
We are an associate professor of computer science and a Ph.D. candidate who are working to shed light on Colorado’s hidden fireflies.
In the past few years, we have observed and filmed elusive bioluminescent fireflies all over Colorado, racing each summer against their brief and unpredictable flashing season.
The authors − Orit, left, and Owen − in the field, taking notes and observing specimens.
Nolan R. Bonnie and Mac Stone
Last year in early June it was too early, we thought, for fireflies in Colorado. For weeks we had been checking weather forecasts, comparing them to previous years, waiting for warmer nights and rising temperatures − the signs that would tell us it’s firefly time.
Then we got a tip. A friend mentioned seeing one or two flashes near their property. The next morning we packed our gear, rearranged our schedules and contacted our volunteer network. The field season began in a literal flash.
As adults, fireflies live and flash for only about two weeks a year − and even then, just for a few hours each night. It’s easy to blink and miss the entire season. The next generation overwinters underground as larvae, emerging as adults the following year, though development may take up to two years in arid climates. Making the most of that narrow window is one of the many reasons we rely on volunteers who help us spot the first flashes and record observations across Colorado.
Western fireflies face unique environmental challenges
Our work joins a growing chorus of scientific observation focused on western fireflies, which pop up across the arid landscape near temporary wetlands, marshes, drainages, desert rivers and other water sources. Because of the dry landscape, these populations tend to be fragmented, isolated to where the water is and nowhere in between.
This strong tie to small, unstable habitat spells vulnerability for the fireflies. If the water runs out, or their habitats are damaged by water or light pollution, the flashing populations could vanish. Pesticides in water are toxic to firefly larvae and their prey, and artificial light inhibits the flash courtship between males and females, preventing successful reproduction. Many populations and species of fireflies are
