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Mertensia virginica en masse.
Mertensia virginica en masse. Photo © Mary Free

Protecting Young Trees from Periodical Cicadas

By Kirsten Conrad, Extension Agent for Arlington County and the City of Alexandria

Because there are currently 15 active “broods” of cicadas that emerge in overlapping cycles, there are some cicadas present every year in most locations. However, Brood X, also called the “Great Eastern Brood,” will emerge in DC, DE, GA, IL, IN, KY, MD, MI, NC, NJ, NY, OH, PA, TN, VA, and WV in 2021. Beginning as early as late April and continuing into June, adults will emerge at sunset from their underground locations where they spend most of their lives 1 to 8 feet below the surface as nymphs feeding on sap of tree roots.

The adult is about 1.5 inches long, mostly black, with red eyes and other reddish markings. The wings are large and clear, except for orange-red veins.

Young, newly planted trees can be vulnerable to severe damage from periodical cicadas. Only the females are known to feed on the leaves, but the real damage is to young branches and trunks of trees ¼-½ inch in diameter that can be killed back by the female cicadas who cut a slit through the bark to deposit 400-600 eggs after mating. Damage is not as serious on older, well-established plants, as only the branch ends will die back. Mating chorusing of male cicadas is very loud, occurring in large aggregations with peak noise usually around 10 am.

  • Flagging damage on a young maple tree.
    Photo © D.L. Clement, UMD
  • Egg laying damage on twig. Photo: Jim Baker, North Carolina State University

Here are some tips and tricks for protecting your new trees: 

  • Avoid planting young trees within one to two years before an expected emergence of periodical cicadas.
  • Netting with a mesh no larger than 1 cm will effectively control injury on branches. Make sure that net is tied well enough to avoid trapping mammals and birds. Tree wrapping with paper tape, tin foil, or similar materials can deter egg laying.
  • Biological control is ineffective because of predator satiation strategy of periodical cicadas.
  • Insecticides are not typically recommended.
  • Dead branch tips can be pruned away and discarded to reduce egg hatch.
  • Make sure to keep your tree healthy. Provide one inch of water per week; stake as needed for up to one year. Remove turf and other ground covers from around the tree to reduce competition for water. Make sure you have chosen and planted your tree species correctly for your site.

For more information, contact the EMG Help Desk at mgarlalex@gmail.com.  

Enjoy the sounds of cicadas from North Carolina State University (video from 2020).

Additional Resources on Cicadas

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