If you've ever heard the loud, vibrating sound of periodical cicadas ebb and flow from your backyard, consider yourself lucky in one respect: You’ve experienced one of nature’s wildest phenomena, the infrequent emergence of these primitive insects. Periodical cicadas only crawl above ground once every 13 to 17 years, but when they do, they can cause damage to young trees. If cicadas are expected in your region this year, plan to cover unsuspecting saplings—as well as your ears!
What Do Periodical Cicadas Look Like?
Periodical cicadas are wedge-shaped and sport large transparent wings, have black bodies with red eyes, and measure about ¾ to 1¼ inches long.
What Is The Life Cycle Of Periodical Cicadas?
After hatching, periodical cicadas burrow themselves in the soil and live there actively for either 13 or 17 years (depending on the species). Once their internal molecular clock signals it’s time—and the soil temp reaches 64°F—they reappear above ground during the summer months. They live 3 to 4 weeks out in the open, providing an animal doesn’t eat them first. While periodical cicadas may not emerge frequently, their life cycles are consistent, making time of appearance easy to predict.
Why do cicadas emerge at all? Well, they’re in search of companions—hence the deafening mating calls the males produce (females don’t sing) during their stint atop the earth.
What Do Periodical Cicadas Do To Trees?
After mating, female cicadas need a secure place to lay their eggs. That safe haven might be the branches of your trees; using a saw-like appendage, a female cicada cuts around 20 rows of ¼- to ½-inch slits into the bark and then lays 24 to 48 eggs in each one (up to 600 per female!). They are particularly fond of the thin branches found on fruit trees as well as any young tree. The slits, which can be as long as 3 inches, can break open thin branches and cause their leaves to turn brown and die (a process called flagging). This can kill the branches of less vigorous trees.
Most cicada damage is usually minimal and happens in their short time above ground, though they do slowly suck tree sap from roots while they’re underground, too. Their subterranean feeding doesn’t kill trees, but it could reduce the amount of fruits and flowers they produce. Thankfully, vegetable plants, flowers, and herbs are not their thing, so your garden should be safe.
What is Brood X?
Because periodical cicadas emerge so rarely, as well as en masse and in sync, scientists can easily track their behavior as different geographical groups, or broods. For example, a group defined as Brood IX emerged in 2020 in southwestern Virginia, West Virginia, and North Carolina after 17 years underground. And 2021 will see Brood X resurface; a group of billions of cicadas stretching across 15 states (from Missouri to New York, and from Georgia to Michigan), Brood X is one of the most prolific in numbers and volume. When they popped up in 2004, their mating hum reached 100 decibels—the same level of noise as a motorcycle engine, power lawn mower, or jet flying over your house.
How Can You Control Periodical Cicadas?
The sheer amount of billions of periodical cicadas emerging at once makes it especially noisy, but their presence is more bark than bite. If you planted new trees this year, or you have fruit trees, simply cover the branches with mosquito netting. Once the cicadas die, rake up their nitrogen-rich shells, crunch them up, and add them to your mulch—they’re a great organic fertilizer for plants.
If periodical cicadas do manage to out-number your efforts and you find damaged branches, remove them right away. An overwhelming infestation can be controlled by using Ortho® BugClear™ Insect Killer for Lawns & Landscapes Ready-to-Spray if needed, too. When applied as directed, it’s safe to use on trees.
There’s no reason to panic if periodical cicadas are expected to emerge in your region this year. Take precautions for your trees and your ears, and you’ll be just fine. With everything protected, you might even enjoy their incredible presence. If cicadas aren’t your thing, the good news is, you won’t have to worry about them for 13 to 17 more years!