On the hunt for fireflies in Utah

Scientists find the flashing bugs after a 30-year search.

  • Until last year, entomologists at Utah’s Brigham Young University hadn’t seen a firefly flash in 30 years of collecting insect specimens.

    Brian Wilcox/ Brigham Young University

On a warm night in June, Nathan Lord, an evolutionary biologist from Brigham Young University, follows a set of abandoned railroad tracks overlooking a spring-fed marsh in Goshen, Utah, a speck of a town once known for mining.

Midway through the marsh, he and colleague Gavin Martin pause between the railway ties to adjust their headlamps, clip on fishing waders, and scan the reeds below for flashes of light, butterfly nets in hand. The first fireflies emerge shortly before 10 p.m., sending a succession of rapid yellow pulses through the dark. Lord’s compact frame disappears down a steep embankment. It’s usually hard to find fireflies in arid Utah, but tonight, hundreds hover above the water.

“Incredible,” says Lord, a postdoctoral researcher who has loved bugs since childhood. “It’s kind of mind-boggling how something so charismatic can basically escape notice.”

Fireflies have captivated humans for centuries and appear in art and literature from around the world. In Japan, they’re so revered that some communities have set aside riparian zones as protected firefly breeding grounds. Early American pioneers trekking across the Plains marveled at them. In her journal, Hannah Tapfield King, a Mormon missionary en route to Utah in 1853, said the fireflies along the Platte River in Nebraska were “like diamond dust over everything at night.”

Fireflies have been documented in Utah since the 1950s, but it wasn’t until recently that entomologists at BYU, despite over 30 years of collecting insect specimens, saw even one flash. They’re rare, but they’re here, at least for now.

How fireflies evaded detection for so long is not entirely clear. They thrive in moist, dark environments, and many species use specific flash patterns to attract a mate. Perhaps it comes down to limited numbers living in high desert regions. Perhaps it’s timing — fireflies live only for a few months in the summer, and few people are willing to linger in mosquito-infested marshes late at night. Or maybe it’s simply that nobody knows they’re here.

Lord and Martin study in the lab of Seth Bybee, an assistant professor of biology at BYU who specializes in the visual systems of insects. Firefly sightings in Utah may become rarer, Bybee tells me. The state is swapping orchards and meadows — prime firefly real estate — for new housing developments for a population that has doubled since the 1980s, especially along the Wasatch Front.

Over the last few decades, meanwhile, scientists have noted a worldwide decline in firefly populations. Possible culprits include pesticides, artificial light and humankind’s ever-expanding pours of concrete. Teasing out the precise cause is difficult, Bybee says, but he suspects habitat loss and increased light pollution, which interferes with firefly communication systems. If the insects can’t find mates, they can’t reproduce. And for Utah fireflies, relocating doesn’t appear to be an option.

“Fireflies are not a great species for dispersing,” Bybee says. “They’re not only pretty tied to a habitat type … the majority aren’t fantastic fliers. They might have more luck moving places back East, but when you live in a desert, you’re not going to be able to go very far.”

Out in the marsh, Lord and Martin sweep their nets through the air. A single bullfrog accompanies a chorus of crickets, as the nets start to fill with blinking bugs fated for a bath of ethanol for DNA preservation, or dissection, or a pin through the thorax — for posterity. Later DNA sequencing by the team could help them develop a theory of the fireflies’ evolutionary history and geographic distribution.

Waist-deep in the reeds, Lord flips a male firefly over by the wings. A wave of yellow light ripples across its abdomen. Lord places it in a plastic vial where it flashes a few times before going dark.

“Now you have proof: Fireflies do exist this far west,” he says. “I can’t tell you how many times I’ve been in situations like this, whether it’s in the United States or in the most well-traveled research station in Costa Rica, and you find a new species literally five feet out the backdoor.”

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