The damage that the periodical cicada produces is from female cicadas cutting slits into twigs and stems of woody plants into which they oviposit (lay eggs). They prefer stems that are 3/16" to 7/16" in diameter, thus the very ends of branches. Very young trees will have a lot longer lengths of their branches in this size range while old, mature, well established trees will have much shorter lengths of their branches in this size range. An individual egg laid into a branch will create a short puncture of no concern. However, the female periodical cicada often lays several eggs in a row one after another making a close line of punctures up to 2–3 inches long. In some locations, periodical cicadas emerge in such high numbers that they can collectively cause heavy damage that results in twig and stem dieback. Large, otherwise healthy trees can withstand this damage without long-term consequences, although they may be aesthetically unpleasing for a time. However, small trees that have a majority of their branches within the cicadas' preferred size range can be severely affected and sometimes be killed. This is especially true of small, stressed trees, such as those that have been recently (within 1-2 yrs. of the emergence) transplanted.

To protect these small, vulnerable trees, we highly recommend using netting over the tree to physically keep the female cicadas away from the branches. Netting only needs to be on the tree during the 3-4 week period that the adults are present.

Although not as effective as netting, chemical pesticides can be used to reduce damage to small trees only when netting is not practical. Chemical control is almost never more effective than netting for private homeowners who want to protect a handful of trees. Most of your chemical protection will come from direct contact kill by spraying the product on the adults present at the time of the application. Synthetic pyrethroids such as permethrin and lambda cyhalothrin have good knock down affects. However, if a product containing one of these pesticides is used, it often will need to be applied every 2–3 days as new cicadas immigrate from nearby areas. DO NOT APPLY a product more often than allowed by the label of the product! Applying these pesticides can also kill beneficial mites and insects that help to manage other insect and mite problems. As a result, other insect and mite pests that are normally not much of a problem can be exacerbated later in the season.

Pesticide applications are not recommended for large, otherwise healthy trees as they can withstand the pressure of cicada oviposition with little to no long-term effects and any aesthetic damage is ephemeral.