See Glowworms Give a Dazzling Show at This National Landmark - National Geographic

August 30, 2021 * National Geographic

BY HEIDE BRANDES

The viridescent mossy glens and labyrinths of rock passageways at Dismals Canyon, in northern Alabama, could easily double for Middle Earth in J.R.R. Tolkien’s epics. But the real magic of this privately owned National Natural Landmark can’t be seen during the light of day. When the sun sets and night settles, tiny glowworms called dismalites shine bright with blue bioluminescence.

Dismals Canyon Natural Area is one of the few places in the United States where these centimeter-long glowworms thrive in impressive numbers, thanks to the unique micro-ecosystem of the area.

Because it is not a national or state park, this natural gem often slips under the radar of visitors—and even longtime residents of Alabama.

“That location has been a popular local tourist attraction going back to the 1920s and ’30s, but it was privately owned, and still is, so it’s never been widely publicized,” says Gary Mullen, professor of entomology emeritus at Auburn University, who helped identify the genus of the dismalites. “You find a lot of people to this day who don’t know it exists.”

The population of dismalites peaks twice a year when the larvae hatch—in late spring and early fall—giving a dazzling show of light, not unlike the fireflies that light up Great Smoky Mountains National Park. But as climate change continues to affect bioluminescent organisms globally, the dismalites population may be living on borrowed time.

What are dismalites?

The glowworms of Dismals Canyon aren’t really worms, but the larvae stage of a unique, native type of fungal gnat endemic to North America called Orfelia fultoni.

Close cousins to the glowworms of New Zealand and Australia, dismalites live in the moist, moss-lined walls of the canyon, the ideal place for them to weave a sticky web to capture prey. They emit a bright blue-green light from both their head and their tail to attract food, usually insects like Alabama’s plentiful mosquitos. Britney Slappey-McCaffrey, Dismals Canyon’s resident biologist, says dismalites illuminate using a process similar to that of fireflies. 

Glowing like constellations of stars, dismalites shine from the wet, moss-covered rock faces of Dismals Canyon in Alabama.

PHOTOGRAPH BY KILIII YUYAN, NATIONAL GEOGRAPHIC

“We have the last primeval forest east of the Mississippi. What that means is that our forest has never been touched by ax or fire, so it's all old timber,” says Slappey-McCaffrey. “It’s almost impossible to get down there with any kind of machinery for farming or lumber. The humidity climate is perfect for dismalites, and the canyon itself was built around their survival.”

Dismalites typically put on their show from mid-April to mid-May when gnats’ eggs hatch, and then peak again mid-September through October.

“I’ve had people tell me that dismalites are in different places in Alabama, but not at the numbers that we have,” she says. “We have the biggest population of dismalites anywhere in the world,” due to the thick Eastern hemlock tree cover at Dismals Canyon which provides the high humidity the insects need to survive.

Glowing, glowing, gone

Although Alabama’s glowworm population is healthy and thriving, not all bioluminescent creatures can say the same.

An abstract published in March 2020 in Insect Conservation and Diversity showed that glowworm numbers have dropped three-quarters from 2001 to 2018, and the climate crisis seems to be the main reason.

Another study published by the Royal Society in July 2020 found that artificial light pollution affects the glow of female insects. In short, when exposed to artificial light, female glowworms are less likely to light up and more likely to hide.

Casper Ohm, a marine biologist and the founder of the Water Pollution Institute, says the amount of artificial light at night is growing worldwide, impacting the behavior of nocturnal organisms, including bioluminescent ones. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, terrestrial arthropods, and microorganisms including some bioluminescent bacteria.

“Light pollutants greatly affect bioluminescent animals, particularly those found on land. Increased exposure to artificial light due to human activities, such as growing cities and increased global shipping movement, may disrupt when and where bioluminescent species occur and disperse,” he says. “In turn, the movement of predators is affected, leading to disruptions in food webs, potentially changing the dynamics of energy transfer efficiency.”

Dismals Canyon is just as delicate. Its precise set of conditions is fragile, and Mullen, who studied the dismalites for more than two decades, says even the smallest change could disrupt the whole magic kingdom.

“Hemlock trees don’t live forever, but they’re living here in a very special environment. Environmental change, climate change, any one of these things could be devastating to that unique population of hemlocks,” Mullen says of northern Alabama’s Eastern hemlock groves, which only grow in the southernmost point of the state.

How to see dismalites

Although many visitors only see Dismal Canyon’s lush grottos while strolling its 1.5-mile hiking trail, some return at night to spy on glowing insects.

Guided night tours occur every Saturday; reservations, which can only be made in person or over the phone, are taken on the Sunday before the following weekend.

Even if you can’t make a night tour, the canyon and its primeval sunken forest are well worth the visit. Excellent places to explore are the Witches’ Cavern and Temple Cave, which were used for sacred rituals and gatherings by Paleoamericans about 10,000 years ago. The greatest number of glowworms in the canyon live in Witches’ Cavern, and the twisty passageways add a hint of mystery and adventure. 

Although the caves have never been excavated, spear points that date to the Paleolithic era have been found in different areas of the canyon; these artifacts are believed to have been left behind by the first humans known to inhabit this part of North America.

When visiting, tourists can help protect the dismalites by keeping their hands off rocks and by treading lightly around canyon walls or beside delicate moss.

“The global glowworm population and firefly populations are really down. You never know what you’re going to get every year,” says Slappey-McCaffrey. “I might have 1,000 [dismalites] down there or I might have 20,000. The climate really is the key to their survival.”