By Richard Rourk
The expected roar of the 2021 brood of 17-year cicadas never quite materialized in much of Unicoi County.
Now that the season’s so far advanced, the unexpected silence from the anticipated insect horde means most Unicoi Countians will have to wait another 17 years for this particular brood to emerge again. In the meantime, experts continue to learn more about these visitors who lives most of their lives at a subterranean level.
“Adult periodic cicadas will stay above ground a month to a month and a half while they breed, and then will die,” Unicoi County ANR/4-H Extension Agent and County Director Chris Mackey told The Erwin Record.
Mackey learned more about these unusual insects after he spoke to Dr. Frank Hale, a professor in the entomology and plant pathology department at the University of Tennessee. He said he learned some interesting things about cicadas from Hale.
“Cicada eggs will hatch in six to seven weeks post-breeding,” Mackey said. “Once hatched, the nymphs will burrow into the ground where they will eat on tree roots and develop until their time to reemerge in 17 years.”
Mackey noted that there is a logical reason why cicadas wait so long to re-emerge.”
Cicada nymphs develop extremely slowly,” Mackey said. “Depending on the brood they will appear either every 13 or 17 years and will also appear in certain areas. Here in Unicoi, we predominantly will only see the Brood X (17-year Cicada).”
What are they doing during all those years beneath the ground?
“Young Cicadas will attach to a root and will suck on the tree sap until it is time to reappear,” Mackey said. “While these insects are considered a nuisance, there is no proof that they cause harm to the roots or the trees they develop on.”
Mackey confirmed that the noise that cicadas produce is a mating call made only by the males. “When the cicadas emerge, the males call the females to mate.”
Mackey described the sound of the insect’s come-hither mating call as a “high decibel clicking sound.”
Mackey noted that there are many common misconception about cicadas. Many people have been informed that cicadas eat fruit, plant foliage and other insects. Some have also been told that cicadas have stinging capabilities.
“All of these statements are not true,” Mackey said. “Adult periodic cicadas tend to only eat the sap of trees,” he said. “However, they are predominately concerned about mating when they emerge from the ground.”
On the other hand, the mymph (developing cicadas) will feast on tree roots while living all those years in darkness beneath the ground. Common trees that cicadas nymphs feed on include but are not limited to oaks, dogwoods, apples, pears and hickory trees.”
Mackey said that cicadas feed by drinking sap from the trees with their piercing-sucking mouthparts, but that doesn’t seem to harm the trees.
“The damage is done by the adult females when they lay their eggs in the live twigs,” Mackey said. “This mechanical damage can cause branch death called flagging. Some of the branches fall to the ground while others stay on the tree. Some of the branches are not killed and will heal. Sometimes apparently healed branches die a couple of years or more afterward.”
Mackey noted that the eggs hatch in six to seven weeks. It’s at that time that the resulting nymphs burrow into the ground and feed on tree roots until they next emergence 17 years later.
In areas where cicadas emerge in abundant numbers, other wildlife, including snakes and birds, will shift their diets to focus on the temporary smorgasbord.
Former Unicoi County resident Toni Hall shared an interesting story about some captive barred owls and cicadas.
“I used to do wildlife rehabilitation in Georgia,” Hall said. “We released two barred owls (Owlfredo and Owlberto) on our farm. That was a big cicada year and we found owl casts that contained nothing but red eyes.”
Owl casts are pellets of indigestible material that owls and other raptors regurgitate after eating prey.
“I wish I had taken pictures of their casts, but this was before cell phones,” Hall said.
Hall said that she believes the two owls purposefully shifted their diet to focus on the abundant prey.
“Plus, they were young, inexperienced birds that had never been fed freshly caught prey,” she said. “I fed them cut up mice or pieces of chicken gizzard dusted in calcium powder, along with the occasional roadkill squirrel parts.
“They spent their days hanging around in the trees near our house,” Hall continued. “Central Georgia had plenty of cicadas that year, so I guess they were attracted to the noise and movement of the insects.”
Experts are in the process of determining exactly how this year’s brood has done compared to the previous Brood X, which appeared in 2004.
“With the cool spring weather, the adults did seem to emerge a few weeks later than normal,” Mackey said. “Adult periodic cicadas usually appear mid-May or when the soil temperature reaches a consistent 64 degrees Fahrenheit.”
For those disappointed at missing the high-pitched, shrill-sounding cicada chorus this year, there’s nothing to do but wait for 2038 when Brood X is scheduled to make its next return.
For more information about these insects, here is a link to the UT publication on periodic cicadas: https://extension.tennessee.edu/publications/Documents/SP341.pdf