Why They Ghost

This dramatic image of Blue Ghost fireflies’ continuous illumination, thought to be a mating dance, was captured in May 2013. 
Photo by Black Visual/Spencer Black Photography

By: Kay West

To really appreciate one of nature’s rarest, most fleeting phenomena, you have to walk into uninhabited woods in the total dark. And that makes most humans very apprehensive. But those who have witnessed the luminous mating dance of the Blue Ghost firefly say the experience is worth straying out of our comfort zones.

“It’s so striking you can’t not be curious about it,” says Jennifer Frick-Ruppert, Ph.D., professor of environmental science, biology, and ecology at Brevard College. Her curiosity was sparked when she came to teach at Brevard in 1997. “I was living in a little cabin set back in the woods, which turned out to be a perfect location for seeing them. I didn’t know what they were, so I caught a few and took them to Clemson University and identified them.”

As she discovered in her subsequent research, the Phausis reticulata, or Blue Ghost firefly, is unique by several standards. The Blue Ghost is found nowhere in the world but the Southern Appalachians and is most populous in the Western North Carolina forest habitat essential to their survival: heavy leaf litter, lots of moisture, and abundant tree cover. The annual hotspots are Pisgah National Forest — which has sections in 12 WNC counties, with the most acreage in Transylvania — and DuPont State Recreational Forest, contained in Transylvania and Henderson counties.

 “Blue Ghosts are the size of a grain of rice,” says Frick-Ruppert. “The females are flightless, the male is not. As forests have been cleared, we lose Blue Ghosts. Imagine something that tiny crawling to a new area to recolonize. It won’t happen.”

Unlike traditional fireflies that blink intermittently, Blue Ghosts emit a steady light. 
Photo by Black Visual/Spencer Black Photography

While all other species of firefly blink on and off as a mating ritual, the Blue Ghost emits a steady glow lasting from 30 to 60 seconds. “With other species, the male flashes in a particular pattern and the female responds in a flashing pattern, like bird song but visual,” explains Frick-Ruppert. “In this species, the male glows and the female glows, but they don’t seem to respond to each other. We can’t figure out what the pattern is, and we don’t know how they communicate with each other.”

The language of love is indeed mysterious. During the one-month mating season, which typically starts in May, the courtship begins when the area is completely dark. The males glow hovering above the ground about knee high; the wingless females glow from the ground. 

The color, from a distance, is a wash of pale whitish-blue — thus their name, says the professor. Up close, the fireflies are more distinct, and the hue is yellow-green. What happens next is not totally unlike human behavior. “We think that with the glow, they are tracking each other. When they actually do find each other and are mating, they cut off their lights,” says Frick-Ruppert with a laugh. “They’re basically hanging out a ‘do not disturb’ sign. We don’t know what happens after that. They are impossible to raise in captivity — you can’t recreate their habitat, so all the questions about their life cycle we can’t answer.”

But experts do know that the trampling of human feet poses great danger to the female and her eggs. “You step on one, and 1,000 potential eggs are gone,” says Frick-Ruppert. “They are being loved to death.” For that reason, DuPont will again close several trails at the High Falls Access Area at night from mid May through early June. 

Dr. Jennifer Frick-Ruppert became an expert on the subject by accident.
Photo by Christie Cauble

At the same time, the Cradle of Forestry will be open after dark for its annual “In Search of Blue Ghosts” nighttime tours. “It’s a great educational and nature experience,” says Director Devin Gentry. “We have a one-mile paved trail, and folks can watch from different stations with Cradle staff or keep walking on their own, as long as everyone stays on the trail.” The tours sell out every year, but he says those living in wooded neighborhoods in the area might also get viewing opportunities. “Put blankets down on the driveway, turn off all lights, and watch for Blue Ghosts from there,” Gentry instructs.

For photographer Spencer Black, who has captured Blue Ghosts in time-lapsed images, it’s a matter of patience and getting down to the ground. “I started going out after fireflies about ten years ago,” he says. “Some years have been really bad, but 2013 was awesome. I’ve never seen them in such numbers. … At their peak, you can’t tell one from the other. It’s like a Jackson Pollock painting times ten.”

The Cradle of Forestry (11250 Pisgah Hwy., Pisgah Forest) hosts the naturalist-led “In Search of Blue Ghosts” Twilight Tour from Tuesday, May 14 through Saturday, May 18; Tuesday, May 21 through Saturday, May 25; and Tuesday, May 28 through Saturday, June 1. 8:30-10:30pm. Admission is $20/general, $10/ages 4-12, with discounts for passholders. Tours are limited to 150 guests and spots fill up fast. For more information, call 828-877-3130 or see cradleofforestry.com.

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