Cicada Brood X: Emerging 2021

The Brood X Cicada population emerges in cyclical patterns every 17 years. Discover why and where this mass emergence will occur, ways this emergence can actually benefit your lawn and fun ways to brood-out in the cicada experience.

What Are Cicadas?

Cicadas are flying, and at times, crawling insects that emerge in warmer  summer months. They are well known for their quintessential ‘shrill’ buzzing mating calls you can hear in the early morning and evenings.

Quick ID

  1. Adult cicadas are about 1-1.5 inches long
  2. Have mostly transparent wings
  3. Range in color, usually black/dark brown
  4. Many populations have green, red or orange markings

What’s their lifecycle?

Cicadas all start as an egg, and morph into nymphs (larvae) where they spend most of their time underground feeding on the root sap of trees. After a few years, the mature nymph will emerge from the soil, attach to an object above ground, shed its outer exoskeleton and transform into an adult flying insect. Adults then look for a mate, breed, and die shortly after.

Are cicadas pests?

Cicadas are more of a noisy nuisance rather than an actual pest. They usually do not cause significant harm or damage to the environment, humans or animals.

Why do cicadas emerge in different years?

Cicadas emerge every year! However, some populations of cicadas emerge annually (e.g. annual or dog-day cicadas), whereas periodical cicadas emerge after longer intervals and in massive numbers. This pattern-driven populations of 3, 5, 11, 13, and 17-year periodical cicada cycles do this for a specific reason – prey satiation.

Prey satiation really just means these insects utilize the method of mass emergence to escape predation and have ample mating opportunities – and it’s a key survival strategy for their species. Why does it work? Predators can’t track the various cicada cycles, so there will always be more cicadas than predators can eat.

Sunday Funday Fact: Different cicada broods occur in different locations and emerge at different times.

What’s Cicada Brood X?

Brood X is a regional population of periodical cicadas that have lived underground for 17 years, and are set to emerge in 2021. Periodical cicadas, like Brood X, feature orange and red colors, but never green. Cicadas that are green in color are annual cicadas.

The emergence of the Brood X population is expected to cover areas of the Midwest, Southeast, and the mid-Atlantic in the United States.


When will they emerge?

The emergence of Brood X will depend on weather, but usually occurs when ground temperatures reach 64 degrees F. This 17-year cicada is predicted to emerge the first or second week of May and should ‘disappear’ by the end of June. But don’t forget – annual cicadas will still emerge and buzz around from June through August.

Sunday Funday Fact: A portion of the 17-year cicada broods have started to emerge 4 years earlier for unknown reasons.

What happens when they emerge?

During this 17-year cycle, cicadas will follow a very tight schedule to ensure successful transformation and mating. Here is the process at a quick glance:

  1. Cicadas crawl out of the ground from areas where they were feeding on sap from tree roots.
  2. Next they’ll climb onto vertical surfaces, including plants, outdoor living materials and manmade structures.
  3. Once settled in, they will molt into the adult (winged) form, leaving their orange-colored exoskeleton behind.
  4. Adults will fly into trees, males will buzz loudly to call for a female and hopefully, they will be successful in mating.
  5. Female cicadas will lay eggs in thin tree branches, and the adults will die off.
  6. Finally, the eggs will hatch and larvae will return back underground for another 17 years.  

How Does Cicada Brood X Affect the Lawn?

While we’ll admit these guys will be awfully noisy, cicadas are essentially harmless to the lawn. Depending on your yard, homeowners may be overwhelmed with large numbers of insects that can cover the grass. Even so, cicadas do not tend to congregate in lawns – you’re more likely to see and hear cicada activity and remnants around trees, woods edge, and wooded areas, (because of habitat, mating behavior and foraging preference).

If they do emerge from your lawn, cicadas will need to crawl out of the ground and will leave a hole where they burrowed in the soil. This is actually a natural, beneficial aeration for the lawn. After cicada eggs hatch, it will be the nymphs that return to the soil, but they’re small (not easily observable) and will not cause any damage when they burrow into the soil.

Sunday Funday Fact: The adults that emerge are not the same ones that re-enter the soil at the end of the season, so there will be a lot of dead cicada carcasses, particularly around trees. This is more of a nuisance than anything, but can also be a natural mulch for your trees.

What Else is There to Know About Brood X?

Good question. Here’s our last fast facts on this incredible insect joining us this summer.  

 Net in Spring or plant in Fall. Brood X can potentially harm small trees planted in Spring 2021 (e.g. now might not be a good time to plant those). Instead, plant new trees this fall or protect your spring plantings with netting.

Cicadas are delicious…? 17-year cicadas like Brood X are an excellent, much needed food source for a lot of creatures – alot of things eat cicadas (including humans!). In fact, their emergence usually correlates to a ‘baby boom’ in birds! 

Avoid pest control. Do not use insecticides on cicadas since it will not control populations. Use of insecticides on cicadas can actually cause unintended harm to other beneficial insects like early spring and summer pollinators.

Compost those exoskeletons. If those leftover cicada ‘shells’ are unsightly to your eyes, add cicada carcasses to your compost. It’s great way to recycle and add free nutrients to your home garden.

Cited Sources

Cornell CALS. New York State Integrated Pest Management. Cornell University

UC IPM. Cicadas. UCANR.

National Centers for Environmental Information. Brood X Cicada Emergence. NOAA. 

National Park Service. Brood X Periodical Cicadas FAQ. US Department of Interior.

Biology. Brood X Cicadas Could Cause a Bird Baby Boom. Scientific American.