Cicadas: What to Know

Medically Reviewed by Dany Paul Baby, MD on January 16, 2023
6 min read

Cicadas are perhaps best known for the loud noises they make. While there are cicadas every year, some species only appear every 13 or 17 years. Whatever their schedule, cicadas are generally harmless.

Cicadas are a family of insects that emerge in the summer months. Their hallmark feature is the loud buzzing sound the males of the species make.

What do cicadas look like? Cicadas have beetle-like bodies with fly-like wings. Their size and color vary between species, but generally, cicadas have:

  • Stout, beetle-like bodies
  • Four clear, fly-like wings with veining
  • A top wing that's longer than the abdomen
  • Very short antennae
  • In males, an organ on the underside of their abdomen that allows them to produce their buzzing sound
  • In females, ovipositors, tubes that allow them to lay eggs

The nymphs, or immature cicadas, often look similar to the adults but do not have wings.

Cicada lifecycle. Female cicadas use their ovipositors to deposit their eggs into tree twigs. Some species will lay their eggs in live twigs, while others prefer dead ones. They hatch as nymphs and drop down to the ground, where they burrow into the dirt. They stay underground for years, feeding on tree and plant roots. The amount of time the nymphs stay underground depends on the species.

When the nymphs are ready, they climb out of the dirt and up a nearby tree or another tall object. There they molt, which gives them wings. A few days after they’ve matured into their adult stage, the cicadas begin mating. The buzzing sounds the male cicadas make is part of their mating ritual. Not long after mating, the female lays her eggs, often between 24 and 48 at a time. Female cicadas can mate multiple times, and some species can lay up to 600 eggs during their lives. Cicadas usually live for three or four weeks after reaching their adult stage.

There are many species of cicadas, and they’re typically divided into two categories: annual (or “dog day”) cicadas and periodical cicadas. 

Annual cicadas. Annual cicadas get their name because, while nymphs may live underground for two to five years, some members of the species emerge every year. In North America, annual cicadas are out from July to September. Various species of annual cicada can be found throughout the world.

Annual cicadas are usually 1 to 1.5 inches long, but some species may grow up to 2.5 inches long. Their bodies are typically shades of green, brown, and black, though some species may have colors like orange, rust, and tan. The veining in their wings is usually black or green.

Periodical cicadas. Periodical cicadas live underground for many years and emerge all at once. There are seven species of periodical cicadas. Three species have 17-year life cycles, while the other four have 13-year life cycles. The year they emerge, they wait until the soil reaches 64°F, usually late spring and early summer.

Periodical cicadas are usually smaller than annual cicadas, ranging from 0.75 to 1.5 inches. They have black bodies, red eyes, and reddish-orange wings. Some species may have yellow bands on their bodies.

Sometimes a portion of periodical cicadas emerge on off years, usually a few years early or late. These are called stragglers.

Scientists aren’t positive why periodical cicadas have such long lifecycles. Some theories suggest that these long intervals underground give them the best chance to avoid predators.

Annual cicadas are found throughout North America and the rest of the world. Periodical cicadas are currently only found in the eastern U.S. and some parts of the Midwest. Researchers have divided periodical cicadas into broods depending on when and where they emerge.

17-year cicadas. There are currently 12 distinct broods of 17-year cicadas. Broods XII, XV, XVI, and XVII were once considered broods but are considered “spurious” now, essentially a false alarm likely caused by stragglers.

  • Brood I, Shenandoah Brood: Brood I is found in Tennessee, Virginia, and West Virginia. They were last seen in 2012 and expected to be seen again in 2029.
  • Brood II, East Coast Brood: Brood II has been spotted in Connecticut, Georgia, Maryland, North Carolina, New Jersey, New York, Oklahoma, Pennsylvania, South Carolina, and Virginia. It last appeared in 2013 and will likely reappear in 2030.
  • Brood III, Iowan Brood: Brood III lives more in the Midwest, in Iowa, Illinois, and Missouri. It last appeared in 2014 and should be back in 2031.
  • Brood IV, Kansan Brood: Brood IV is another Midwest brood, found in Iowa, Kansas, Missouri, Nebraska, Oklahoma, and Texas. It was last seen in 2015 and should reappear in 2032.
  • Brood V: Brood V has been seen in Maryland, Ohio, Pennsylvania, Virginia, and West Virginia. It last emerged in 2016 and should reemerge in 2033.
  • Brood VI, Bushy Mountains Brood: Brood VI inhabits Georgia, North Carolina, and South Carolina. They appeared last in 2017 and are expected to appear again in 2034.
  • Brood VII, Onondaga Brood: Brood VII has only been seen in New York. It last appeared in 2018 and should appear again in 2035.
  • Brood VIII: Brood VIII is found in Ohio, Pennsylvania, and West Virginia. It was last seen in 2019 and should be seen again in 2036.
  • Brood IX: Brood IX is found in North Carolina, Virginia, and West Virginia. It was last seen in 2020 and should appear again in 2037.
  • Brood X, Great Eastern Brood: Brood X can be found in Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. It last appeared in 2021 and should be back in 2038.
  • Brood XI: Brood XI was once found in Connecticut. It last appeared in 1954 but is now extinct.
  • Brood XIII, Northern Illinois Brood: Brood XIII is found in Iowa, Illinois, Indiana, and Wisconsin. It was last seen in 2007 and should be seen again in 2024.
  • Brood XIV: Brood XIV lives in Kentucky, Georgia, Indiana, Maine, Maryland, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. It last emerged in 2008 and should emerge again in 2025.

13-year cicadas. There are currently three broods of 13-year cicadas. Several broods are now labeled “spurious,” and brood XXI is considered extinct.

  • Brood XIX, Great Southern Brood: Brood XIX has been found in Alabama, Arkansas, Georgia, Indiana, Illinois, Kentucky, Louisiana, Maryland, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, and Virginia. It last appeared in 2011 and should be back in 2024.
  • Brood XXII, Baton Rouge Brood: Brood XXII has been found in Louisiana, Mississippi, Ohio, and Kentucky. It last emerged in 2014 and should emerge again in 2027.
  • Brood XXIII, Lower Mississippi Brood: Brood XXIII lives in Arkansas, Illinois, Indiana, Kentucky, Louisiana, Missouri, Mississippi, and Tennessee. It was last seen in 2015 and should be back in 2028.

You’ll likely hear the cicadas before you spot them. Most cicadas make an electric buzzing sound, but some make other sounds like a high-pitched screech or a ticking noise. These calls can be loud: some species of cicadas can reach a volume of nearly 109 decibels. That’s somewhere between a hand dryer and leaf blower.

Cicadas feed on trees. If you find one in your house, it probably got in by accident. 

Outdoors, cicadas prefer woody and forested areas. If your yard has a lot of trees, you’re more likely to see cicadas.

Cicadas do not bite and do not pose health risks to humans or pets.

Though they can be loud, cicadas are relatively harmless. They can, however, sometimes damage trees when they lay their eggs or when the nymphs feed on the roots. Newly planted and smaller trees are more likely to sustain damage from cicadas.              

You can protect vulnerable trees by covering them with fine netting or cheesecloth to prevent female cicadas from getting at the branches to lay their eggs. Removing small, damaged branches can help reduce the future population. It’s also a good idea to hold off on planting new trees until later in the summer.

Using chemical sprays on cicadas is not recommended. This can poison other insects and the animals that eat those insects.