Conservation Outdoors Sustainability

Sustainability: The Wild Truth

A Starry Night with Glow Worms

Green Glow Cave. Photo by Donnie Ray Jones

By Winslow Umberger

One of the beauties of living in these mountains is the easy access to dark skies. Within minutes, one can drive to an overlook on the Blue Ridge Parkway and marvel at the majesty of the firmament. What a singular experience, or so I thought, until a recent trip to New Zealand. Their caves seemingly contain fields of stars—a spellbinding phenomenon created by the tiniest and humblest of creatures: glow worms.

These bioluminescent larvae of fungus gnats (Arachnocampa luminosa) live deep inside caves mimicking stars to attract prey. Unwitting insects fly up into a faux night sky only to be entangled in elegant fine fishing lines of silk suspended from the ceiling. Droplets of moisture cling to these silken threads, resembling delicate, dangling pearl necklaces affixed in place by bluish “clasps” of light—the larvae of glow worms.

Regardless of time of day and weather conditions, the glow worm caves of New Zealand offer a unique celestial experience. Exploring the Metro/Te Ananui caves of Charleston on the South Island is for the more adventurous. This involves hiking through a rainforest to the cave entrance, carefully spelunking around stalactites and stalagmites with head lamps and then plunking into an inner tube in icy water. Little can match the wonder of gliding, in complete silence, through a three-dimensional milky way of stars scattered high above in an ancient cave.

Photo by Joseph Michael

Such lengths are not necessary to experience this marvel. The Waitomo Caves on the North Island are accessible to anyone of any ability. A pedestrian-friendly path winds through fascinating rock formations to a boat docked in the heart of the cave. Seated passengers are silently transported on an inky black river through a glowing galaxy of lights sprinkled across the low-vaulted ceiling of this 30-million-year-old cave. Either way, you will be spellbound.

But you don’t need to travel halfway around the world to experience glow worms. Fortunately, they live amongst us.

“The term ‘glow worms’ often refers to firefly larvae,” says the Great Smoky Mountains National Park’s entomologist Dr. Becky Nichols. “However, there are other groups that often are referred to as glow worms. These include adult females of some firefly species which are larviform (i.e., they look like larvae and don’t have wings) and glow. There are also glowworm beetles, whose larvae and females glow, and the predatory fungus gnats who glow in this area called Orfelia fultoni, in the family Keroplatidae. Fungus gnats live in drippy, mossy crevices and have a faint glow to attract prey.” These are in the same family as the ones seen in New Zealand.

Glow worm filaments. Waitomo Caves. Photo by Winslow Umberger

Whereas the New Zealand glow worms dangled sticky filaments from cave ceilings, glowing firefly larvae can be found faintly shimmering in leaf litter. Not as dramatic for sure but magical nonetheless. Who would imagine these predators actively moving along the forest floor snaring small invertebrates with large, hollow mandibles and injecting them with toxin? Both families of glow worms are carnivores, but only a few species make hunting look so spectacular, attracting admirers from around the world.

Those wishing to experience the fantastic lightshow of Orfelia fultoni will need to make the roughly 4-hour drive to Hazard Cave in Tennessee’s Pickett State Park. These marvelous wonders can also be experienced at Dismals Canyon in Franklin County, Alabama. Summertime is the best time to visit. For those looking for an excuse to see how the Southern Alps compares with Appalachia’s bluish beauties, including spelunking for glow worms, is a great place to start your adventure. This company has a host of glow worm cave-viewing options that can be combined with experiencing this country’s natural splendors.

No matter where you live, there are countless wonders to be found all around you. Making the time to explore, whether it be off the beaten path or simply looking underfoot—as with the tiny lights luminating humble leaf litter—will not only deepen your appreciation for the natural world but leave you glowing with awe at Nature’s seemingly boundless ingenuity.

Winslow Umberger is a board member with Appalachian Wildlife Refuge, a nonprofit focused on helping save and protect native wildlife as well as providing conservation education. Visit for more information. Found an animal in need? Call its wildlife hotline at 828.633.6364.

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