Cicadas and Your Trees

17-Year Cicadas of Brood X Emerge Soon -- What You Should Know

What were you doing in 2004? Watching Napoleon Dynamite? Creating your profile on a new site called “Facebook”? If you lived in Tennessee, whether you knew it or not, Brood X (which you pronounce as “ten”) periodical cicadas could be found under your very feet, waiting for their May 2021 emergence.

This spring marks a very special year for the Brood X cicadas, which will emerge from the ground in a 17-year cycle. They won’t live very long — two to six weeks (according to most sources), just to mate and lay eggs — but they’ll be a nice, loud harbinger of the summer to come. Some periodical cicada species emerge every 13 years, and the annual cicadas you are used to seeing and hearing every southern summer are actually larger than what you will see in Brood X. Another difference you might notice between the three periodical cicada species that make up Brood X, and the annuals? Brood X have red eyes!

Ominous optics aside, this emergence will not be apocalyptic. We’ve received a lot of questions and concerns about these cicadas, but our most important message is: don’t panic. Take a breath to still the buzzing in your brain (there will be enough buzzing coming soon), and check out these factoids to learn more about what to expect.

  • Like Haley’s Comet, consider this emergence to be the special event that it is. Instead of thinking about this occurrence as a potential nuisance, reframe your perspective. How fascinating is it that this event takes place only once every 17 years?!
  • Nashville’s Brood X emergence is not expected to be extreme; within the state, East Tennessee is predicted to experience the greatest number of cicadas. Read more here (“After 17 years, Brood X cicadas to emerge in Tennessee for a noisy, speed dating free-for-all,” Knoxville News Sentinel). Overall, Washington D.C. is expected to be the epicenter.
  • Any potential threat to newly planted trees comes from where the cicadas lay their eggs: in slits at the tips of tree twigs. Starting in spring, and especially over the summer, trees take advantage of the sunlight to grow in both height and width. To grow in height, new cells are formed at these twig tips, and so cicada egg-laying could potentially inhibit growth. (Learn more about how trees grow.) These eggs will hatch in six to ten weeks, and then the baby cicadas fall to the ground, bury themselves, and live underground for 17 years.
Example of what a tree branch looks like from cicada egg-laying
Source: Tree Topics, The Bartlett Tree Experts Blog
  • Words of wisdom from Eric Kuehler, Metro Arborist at Metro Water Services: 

Davey explains that cicadas damage trees partly by damaging small branches in which they lay their eggs, but mostly by feeding on roots belowground for up to 17 years before they emerge. This cycle has been going on for thousands of years, so I am not too worried about it. In the link above, Davey does add some advice about caring for newly-planted trees. If you see slits in small branches of trees from June to September, you may want to prune those branches off the tree to remove the eggs. We would like to prevent the newly-hatched cicada from getting belowground and eating the roots.”

  • If you are particularly worried about protecting your newly planted trees, a breathable net placed loosely and gently over your tree, secured at the bottom, should do the trick.
  • Pesticides are not recommended and would do more harm than good. They pollute the environment by contaminating our soil and water, and hurt wildlife.
  • Unless your dog is particularly neurotic, the cicadas should pose no threat to your pets!

Brood X is expected to come aboveground in mid- to late-May. Enjoy the quiet spring while it lasts, but we hope you will also take wonder in this incredible spectacle.


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