This summer should be a noisy one for much of the Eastern U.S., since two broods of periodical cicadas are expected to emerge nearly at once.
One of them is the 13-year Brood XIX and the other is 17-year Brood XIII.
While some cicadas emerge from the ground every year, certain species take longer to mature. According to the University of Connecticut, these periodical cicadas “are among the most unusual of insects, with long life cycles, infrequent, periodic mass emergences, striking appearance, and noisy behaviors.”
Cicada sounds may seem even more extreme during this year’s double emergence since periodical cicadas have been hiding during recent years.
“Late spring and early summer in the forests of the eastern half of the U.S. have been eerily quiet for the past two years,” said a report in Scientific American. “In most years, long-lived periodical cicadas thrum through the region, but a quirk of timing means these insects have been sparse since 2021.”
Here’s what to expect
A single cicada can lay around 600 eggs and periodical cicadas can achieve population densities, as high as 1.5 million per acre. Their unusual life cycles protect cicadas from predators, and they don’t have any defense mechanisms such as stinging or biting. Additionally, they are not known to carry disease.
Brood XIX is the largest of all periodical cicada broods, per the University of Connecticut. Records indicate it extends along the East Coast from Maryland to Georgia and into the Midwest from Iowa to Oklahoma. Its northernmost distribution is in Chebanse, IL, roughly 75 miles from Chicago’s Loop. Brood XIII is called the Northern Illinois Brood. It is known for having off-season emergences.
While life cycles of periodical cicadas are determined by a yet-unknown mechanism, it is clear that emergence is tied to soil temperature.
“Periodical cicada emergences occur when soil temperatures at a depth of 7-8 inches reach approximately 64°F,” the University of Connecticut explained. For this reason, cicadas emerge faster further south, often in the spring, and in the summer further north.
Periodical cicadas are white shortly after molting but quickly develop a signature appearance that includes black bodies, red eyes and orange wing veins. Adults feed by sucking plants, and males from each species produce a specific calling sound to attract females.
Eggs from periodical cicadas hatch after six to ten weeks. Nymphs then drop from trees and bury underground to begin the cycle again. By the time this process occurs, the adults that emerged from the ground at the start of the season have died.
According to the U.S. Environmental Protection Agency, cicadas are not harmful to humans, pets, household gardens, or crops. It also said their appearance has benefits, including: being a valuable food source for birds and other predators, aerating lawns, improving water filtration into the ground and adding nutrients to the soil as they decompose.
If people do have a need to manage cicadas during the “cicada-geddon” (as the Associated press termed it), the EPA notes that pesticides are ineffective at reducing their numbers. The agency simply recommends protecting young trees from the cicadas with mesh. People in the cicada brood coverage area may want to plan outdoor events around the emergence if they are worried about the noise.