Blue Ghost Fireflies –
Rare, Mysterious, and Probably in Your Yard!
I gasped when I first spotted them, then I burst into tears and laughter simultaneously. Witnessing Blue Ghost Fireflies (Phausis reticulata) is a surreal experience. Southern Appalachia is the only place in the world to experience this magical phenomenon.
Imagine thousands of firefly ‘fairies’ gliding above the forest floor on a dark, quiet, late spring night. They don’t flash or blink – they glow. And not bright yellow like an ordinary firefly but a constant soft blue-green. You’ll rub your eyes and blink a couple of times because you’re not sure if you’re ‘seeing things.’ The impressive display occurs between mid-May through mid-June from 9:30-10:30pm right here in Sherwood Forest.
The Blue Ghost fireflies are not actually flies as the name implies but tiny brown beetles. The size of a grain of rice, the males fly just above the forest floor seeking a mate. They emit an otherworldly blue-green light that stays on for up to a minute hoping the females will glow in response to their mating display. The females are wingless and emit a soft bioluminescence to attract their mate. When the male comes close to the female on the forest floor, he extinguishes his light and tries to cover her glow while they mate.
As visual creatures, they need darkness to see each other’s signals, so porch lights, street lights, flashlights, cell phones and even a bright moon can inhibit their activity.
Though harmless to humans, the vicious little predators are carnivorous and will eat any bug or slug smaller than themselves! They are sensitive to soil temperature for their transition into adulthood and have been emerging earlier in the year due to climate change. The almost transparent female will dry out because she has a thin exoskeleton and the males can’t fly in heavy rain so drought and flooding can also impact their population.
The tiny insects are found in very specific microhabitats of undisturbed moist leaf litter in old growth forests. They prefer north facing slopes often near a cove creek bed. Because the females remain in a relatively immobile larval stage even when sexually mature, recolonization of a disturbed area is almost impossible, hence their shrinking range. Some trails in nearby Dupont State Forest are temporarily closed during mating season to protect their habitat.
Little has been published about the insects but Brevard College Professor Dr. Jennifer Frick-Ruppert has been studying them for the past 15 years after finding only one article dating to the 1960s. Interest in the fireflies has swelled in part due to the popularity of their Synchronous cousins (Photinus carolinus), a resident of the Smoky Mountains, in which both the male and female can fly. The two rare species occupy the same type of habitat but the Synchronous fireflies have the advantage of mobility.
For optimal viewing, nothing is needed except the willingness to stand quietly in the dark. You may want to cover a flashlight with blue or red cellophane so as not to stumble when you make your way to the woods. Then turn off your light, let your eyes adjust, and prepare to be enchanted.