Smoky Mountain Cicadas. What’s all the buzz about?
A rare natural history event is unfolding right now! This month through mid-July, billions of 17-year periodical cicadas are expected to emerge across the eastern United States. Grab your earplugs and get ready! Periodical cicadas are a group of species that don’t emerge yearly, they emerge in 13- and 17-year cycles.
“We’re already getting reports of periodical cicadas emerging around Knoxville,” said Becky Nichols, entomologist for Great Smoky Mountains National Park. “We expect to find them on the western side of the Smokies from Look Rock to Cades Cove, but we’re not exactly sure. We have several park volunteers keeping eyes and ears out for them.”
This summer’s cluster of emerging periodical cicadas is called Brood X, which includes the pharaoh cicada (Magicicada septendecim), the dwarf periodical cicada (M. cassinii) and the decula periodical cicada (M. septendecula). Unlike the black and green annual cicadas that emerge later in the summer, periodical cicadas are predominantly black with amber colored wings and red eyes. Subtle characteristics on the underside help to distinguish the different species.
Cicada nymphs are digging their way out of underground burrows, where they’ve been feeding on sap from tree roots for the last 17 years. Each nymph crawls up the side of a tree or other nearby structure and begins to molt. After a few hours, the newly emerged adult is ready to fly and leaves its empty brown exoskeleton behind.
“Looking for ‘cicada shells’ is one of the best ways to tell if you’ve got cicadas around you,” said Todd Witcher, executive director for Discover Life in America, a Smokies nonprofit partner organization. “And right now, you know they’re periodical cicadas because those are the only ones emerging this early.”
A few days after the males emerge they will begin to sing from nearby trees. As more and more individuals emerge and sing, their chorus can reach 100 decibels — louder than a lawn mower.
What’s all the buzz about? These cicada males are looking for love! Males sing to entice females to mate. Each of the three Brood X species has a distinctive, chattering call to help them sort each other out.
Once mated, each female makes slits in tree twigs, which doesn’t cause long-term damage to the tree, and deposits around two dozen eggs into each slit. She can lay up to 600 eggs. In a few weeks nymphs hatch from the eggs and drop to the ground. They then burrow down to find tree roots. They will feed and grown the roots until the next mass emergence of Brood X in 2038.
Adults live only a few weeks giving them enough time to sing, mate and lay eggs. By June to mid-July the forest floor will be covered with their lifeless bodies, which will slowly break down and nourish the trees that will feed their progeny.
“The thought of a bunch of flying, buzzing bugs may be frightening to some,” said Nichols, “but there is nothing to fear. Cicadas are harmless—they don’t bite or sting or harm trees, people, or pets, and they’re an important source of nutrients for the many animals that eat them.”
You can help further knowledge on this amazing event by reporting any 17-year cicada sightings through several community science platforms, including iNaturalist (inaturalist.org) and Cicada Safari (cicadasafari.org). These records help scientists like Cooley and Nichols better understand the distribution of periodical cicadas so these noisy yet charismatic insects can be protected for future generations to enjoy.
HeySmokies would like to extend a special thank you to Will Kuhn, Director of Science and Research at Discover Life in America for his expert contribution. Discover Life in America seeks to discover, understand and conserve the biodiversity of Great Smoky Mountains National Park. Learn more at dlia.org.