After a 13-year nap, cicadas are waking up in the South, and with them comes an ear-splitting mating call that will soon fill the air across the southern U.S.
The 13-year cicadas of what is known as Brood XIX (the 19th brood) have been living underground since 1998. That was the last time they held their famous two-month, above-ground mating frenzy.
Brood XIX, also known as the Great Southern Brood, is the country's largest group of 13-year cicadas, stretching across 12 states, including Missouri, South Carolina, Oklahoma and Illinois. Already rising in some parts of Georgia, they should all be hatched by mid-May.
The low-pitched mating calls, all produced by the males of the species, are already so loud that some Georgia residents have mistaken them for the howl of a tornado, according to the Atlanta Journal-Constitution.
That's a lot of noise for an insect that's only an inch-and-a-half long. But despite their daytime racket, they are otherwise harmless, University of Georgia entomology professor Nancy Hinkle told the Athens Banner-Herald. "The only minimal problem is that the females lay eggs near the ends of tree branches, and that causes browning of the leaves and might cause the branch tips to fall off. But even that's just nature's pruning service — so next winter, the whole branch won't come off in an ice storm."
Meanwhile, the cicadas provide two important environmental roles. First, they provide a good supply of food for local predators. Second, after their two-month breeding cycle, the dying cicadas will help support the very trees they feed off of: "When they die, their carcasses essentially decay and provide a nice nutrient injection back into the soil for the trees," Gene Kritsky, editor-in-chief of the journal American Entomologist, told NPR.
While the cicadas have already erupted from the soil in Georgia's Crawford County, it may be a few weeks before they emerge elsewhere. Kritsky says the insects will rise from their slumber in other areas when the local soil reaches 65 degrees.
Although their mating calls may be a loud nuisance — hitting up to 85 decibels in places where the insects are most concentrated — it won't be enough to cause any damage, a fear that some Southerners have expressed. "It won't damage anyone’s hearing," Missouri University biology professor Johannes Schul told the Missourian. "If we were exposed to those levels of noise for years at a time, then we might face an effect, but this outbreak is short and will not have any adverse health effects aside from stressing a few people out."
These periodical cicadas emerge in 17- and 13-year cycles and shouldn't be confused with a variety of cicadas that can be heard every summer. There are three broods of 17-year cicadas, one of which will appear in the summer of 2017. Brood XIX will next rise in 2024.