Brood XIV cicadas are expected to emerge in some parts of the New York City area in 2025 as soil temperature reach a threshold in the mid-60's.  This brood of 17-year cicadas includes all three species that have a 17-year lifecycle: Magicicada septendecim (the Pharaoh cicada), Magicicada cassini (dwarf periodical cicada), and Magicicada septendecula (little 17-year cicada).

The cicadas appear from the ground as mature nymphs and move up the trunks of trees and shrubs. After the winged adult cicadas emerge from their casing they are on the move for less than a month before females lay eggs. The eggs are present on plants for up to two months, hatch, and then nymphs fall to the ground where they remain for 17 years. Underground, they attach themselves to roots and feed from them as they mature, though the related damage to plants from this extended feeding is usually minimal.

Cicadas may damage your woody plants during their egg laying phase, but most healthy, established trees are at little risk. Recently planted trees and shrubs, particularly fruit trees, are at greater risk of damage. Female cicadas cut into the bark of trees and shrubs at the branch tip where there is relatively soft, year-old growth of about a pencil's diameter. A single female may deposit over 500 eggs on the plant, moving from one branch to another, and the numerous egg incisions can create branch damage, wilting and  tip dieback.

For healthy, mature trees the impact should be relatively minor. Insect density in the area and the supply of trees to lay eggs on will both influence the potential for greater harm to trees; more insects laying eggs on fewer trees is more damaging. The cicada activity may result in trees with bundles of dead leaves only at the limb tips later in the summer (called flagging) or small piles of dead leaves and twigs on the ground under the trees. Look for the telltale incisions made by the females when you see this phenomena.

Young trees are more attractive as a laying site because of they are covered in softer bark and may suffer more damage. For fruit trees where these impacted young limbs would become the productive scaffolding branches, damage can be more problematic.

Before egg laying begins, young trees can be protected by covering the canopy with mosquito netting and tying it below the lowest branches, creating a physical barrier to cicadas. Take care not to make the covering so tight that it causes injury to the branch tips or chafes the trunk. It can be removed about a week after the loud mating calls of the male cicadas has ceased. 

If you find slits in the tips of your tree's branches where eggs have been laid but not yet hatched, you can prune them off and dispose of them if you'd like to keep the nymphs from returning to the soil around the tree. 

Vigorous trees will heal as the season progresses. Offer damaged trees support while they heal themselves by watering during dry periods.

Additional Information:

The website Cicadamania offers this Guide to Identifying Cicada Species.

For photos of the incisions made by the female cicadas when they lay eggs and the appearance of dead leaf bundles on affected branches, see Managing Cicada Damage to Trees from The Virginia Cooperative Extension.

Courtesy of NYBG Plant Information Service