The 17-year, periodical cicadas are coming to Fairfax County in early summer. When the soil temperature warms to about 65 degrees Fahrenheit, the newly mature, soil-dwelling cicadas will begin to emerge from their underground homes, leaving an emergence hole about the size of a dime.
They may be noisy, but they are not a threat to people or animals. Cicadas are harmless and do not bite or sting. These brood hatches are a bounty to local wildlife and full of protein. It’s an all-you-can-eat buffet for birds.
However, there is a minor concern for trees. Adult cicadas lay their eggs (or oviposit) in live twigs. These affected branches will likely fall to the ground, allowing the newly hatched cicada, or nymph, to again burrow into the soil. This is a natural phenomenon that trees tolerate well. However, the sheer number of insects laying eggs may result in some twig dieback, especially on younger trees. The damage is largely cosmetic, but residents may choose to protect newly planted or young trees by placing fine netting, such as used for fruit protection, around the crown. Select netting that is 3/8 inch or smaller and secure it around the trunk. It is also advisable to delay planting new trees until the fall and the risk of cicada damage has passed.
The 17-year cicadas are unique in that they spend most of their life cycle in the ground feeding on plant roots. When they come out in early summer they must find a mate, lay their eggs and hatch the next brood of insects. Several, separate broods are known to occur at staggered intervals across the eastern United States.
For more information about cicadas and other tree pests, contact the Urban Forester of the Day at 703-324-1770, TTY 711 or email@example.com.