Across North America, the telltale signs of cicada damage begin appearing in late spring and early summer. Patches of lawn develop brown, scorched-looking areas, and young trees show torn bark and wilting branches. These symptoms are not the work of disease or drought, but rather the result of a synchronized natural event carried out by insects emerging after years, or even decades, underground.
Understanding the Cicada Life Cycle and Feeding Habits
The life cycle of a cicada is the primary reason for the specific type of damage observed. While the loud, buzzing adults grabbing headlines are the most visible stage, it is the nymphs living underground that cause the initial stress. These nymphs feed on the xylem sap from tree roots, a process that generally does not harm the tree. The real destruction occurs when the nymphs molt into adults and the females lay their eggs.
Egg Laying and Branch Damage
Female cicadas use a saw-like ovipositor to cut slits into the twigs of deciduous trees to deposit their eggs. This physical incision disrupts the flow of nutrients and water, effectively girdling the branch. While a few cuts are insignificant, heavy infestations can lead to flagging—where the leaves on the end of a branch turn brown and die—and in severe cases, the death of the twig. This targeted damage is the most direct and costly impact on landscaping and young orchards.
Turf Damage and Soil Activity
Above ground, the activity of the emerging nymphs and the subsequent molting process create visible scars on lawns. As nymphs crawl up the trunk or nearby vegetation to molt into winged adults, they leave behind distinctive crescent-shaped cuts in the soil. Furthermore, the feeding tunnels created by the nymphs underground can disrupt root systems, leading to patches of grass that dry out quickly and turn brown, resembling drought stress.
Long-Term Tree Health and Vulnerability
Mature, healthy trees typically withstand cicada populations with minimal long-term effects, treating the event as a minor seasonal stressor. However, the equation changes for younger trees or those already compromised by drought, disease, or poor soil. The energy expended by a tree to repair the damage from egg-laying and to recover from root disturbance can stunt growth for several years. Repeated heavy cycles can push a weakened tree to decline.
Species-Specific Impact
Not all cicadas are created equal when it comes to destruction. Periodical cicadas, such as the Brood X emergence, are generally less damaging than annual "dog-day" cicadas. The sheer volume of periodical insects creates a saturation effect; predators like birds and wasps become sated quickly, leaving many nymphs and adults unharmed. In contrast, the annual cicadas that appear every summer are often more effective at targeting specific trees due to their concentrated numbers and focused egg-laying behavior.
Mitigation and Recovery Strategies
Homeowners and landscapers can take proactive steps to reduce the impact of cicada damage, particularly for valuable ornamental trees. Applying row covers or fine mesh netting to small trees during the peak egg-laying weeks of late spring provides a physical barrier. For existing damage, pruning affected branches helps the tree redirect energy to healthy growth, and applying mulch around the base supports root recovery by retaining moisture and regulating soil temperature.
