How to Safeguard Trees from 17-Year Periodical Cicada Damage

Every 17 years, millions of periodical cicadas emerge from the ground, filling the air with their distinctive buzzing and clicking sounds. While these insects are a fascinating natural phenomenon, their emergence can pose significant risks to young trees and shrubs. Understanding how to protect your trees during this time is crucial for maintaining a healthy and thriving landscape.

In this comprehensive guide, we’ll explore the biology of 17-year periodical cicadas, the nature of the damage they cause, and practical strategies you can implement to safeguard your trees.

Understanding 17-Year Periodical Cicadas

Life Cycle and Behavior

Periodical cicadas belong to the genus Magicicada and are known for their synchronized emergence every 13 or 17 years, depending on the species. The most well-known are the 17-year cicadas, which spend 17 years underground as nymphs feeding on root sap before emerging en masse as winged adults.

Once they surface, adult cicadas live for about four to six weeks. During this time, males sing to attract females, and after mating, females lay eggs in tree branches. The young nymphs hatch and drop to the soil to burrow underground, continuing the cycle.

Why They Are a Concern for Trees

While adult cicadas do not bite or sting humans and cause no direct harm through feeding, their egg-laying process can injure trees. Females use a specialized organ called an ovipositor to cut slits into small twigs and branches where they deposit eggs. This behavior can cause:

• Flagging: Twigs and small branches may wilt and die due to the damage caused by egg laying.
• Structural Weakness: Heavy egg-laying can weaken branches, leading to breakage.
• Overall Stress: Repeated damage over multiple years can stress young or vulnerable trees.

Larger, mature trees usually tolerate cicada damage better than smaller ones, but protecting all trees , especially fruit trees and ornamentals , is advisable during cicada emergences.

Identifying Cicada Damage

Before diving into protection strategies, it’s important to recognize signs of cicada-related injury:

• Wilting or dying branch tips: Often called “flagging,” this appears as brown or dead ends on twigs.
• Small slits or cuts: Made by females’ ovipositors in young branches.
• Excessive twig breakage: Due to weakened wood from egg-laying activity.

If you notice these signs during cicada emergence years (notably 2024 for Brood X in many regions), consider taking protective action.

How to Protect Trees from Cicada Damage

1. Use Physical Barriers: Netting and Screens

One of the most effective ways to prevent female cicadas from reaching tree branches is installing physical barriers.

• Fine Netting: Use lightweight mesh netting with holes smaller than 1/8 inch (3 mm) in size. This prevents cicadas from accessing branches while allowing light and air through.

• Timing: Install netting just before cicada emergence begins (early spring) and keep it on until after the adult cicadas have died off (about 4-6 weeks).

• Application Tips:

• Cover the entire tree or vulnerable shrubs completely.
• Secure edges tightly at the base with stakes or weights to prevent cicadas from crawling underneath.
• Remove netting carefully after emergence to avoid damaging new growth.

This method is particularly useful for protecting young fruit trees and newly planted ornamentals that are most susceptible to damage.

2. Delay Pruning Until After Emergence

Pruning encourages new growth , precisely what female cicadas seek out for egg-laying. If possible:

• Avoid heavy pruning in early spring just before cicadas emerge.
• If pruning is necessary, do it after the emergence window when adult cicadas have disappeared.

This minimizes tender new growth exposed at peak egg-laying time.

3. Maintain Tree Health Through Proper Care

Healthy trees recover faster from any damage inflicted by cicadas.

• Watering: Keep trees well-watered during dry periods.

• Mulching: Apply organic mulch around tree bases but avoid piling against trunks.

• Fertilization: Use balanced fertilizers if recommended based on soil tests.

Vigorous trees are better able to compartmentalize damaged areas and produce new growth quickly.

4. Use Insecticides with Caution

Chemical control of periodical cicadas is generally not recommended because:

• Cicadas only emerge once every 17 years; thus repeated chemical treatments aren’t practical.
• Many insecticides are ineffective against adult cicadas due to their short above-ground lifespan.
• Broad-spectrum insecticides can harm beneficial insects like pollinators.

If you choose this route:

• Target young nymphs below ground (which is difficult).
• Use systemic insecticides only if recommended by a professional arborist or extension service.

For most homeowners, physical barriers are safer and more environmentally friendly.

5. Encourage Natural Predators

Birds such as crows, blue jays, and sparrows feed heavily on periodical cicadas during emergence years. Encouraging wildlife habitat in your area can naturally reduce local cicada populations.

• Provide bird feeders and water sources.
• Preserve native vegetation that supports predators.

Remember that natural predation alone usually does not eliminate damage risk but can be part of an integrated approach.

Protecting Specific Tree Types

Fruit Trees

Fruit trees are especially vulnerable because female cicadas prefer tender new growth which fruit trees produce abundantly every year.

Recommendations:

• Cover young fruit trees with fine netting during emergence years.
• Avoid pruning until after peak emergence.
• Monitor flagged branches closely; prune out damaged parts post-emergence to promote healthy regrowth.

Ornamental Shrubs and Trees

Many ornamental varieties also suffer from twig dieback due to egg laying.

Recommendations:

• Use netting on valuable specimens where feasible.
• Maintain overall plant health using watering and fertilization best practices.

Mature Shade Trees

Older shade trees typically sustain minimal long-term damage but can still experience twig flagging.

Recommendations:

• Prune dead twigs after emergence without worry about structural impact.
• Ensure general tree health through proper care routines.

What To Expect After Cicada Emergence

After the adult phase ends:

• Most damaged twigs will dry out and fall off naturally or with light pruning.
• Trees may experience some stress but generally recover quickly if healthy.

If significant branch loss occurs:

• Water deeply during dry spells.
• Fertilize appropriately in late spring or early summer following local guidelines.

With good care, your landscape should return to normal well before next cicada emergence decades later.

Conclusion

While the spectacular emergence of 17-year periodical cicadas can be a challenge for tree lovers, understanding their life cycle and damage patterns empowers you to take proactive measures. Physical barriers like fine netting applied at the right time remain the most effective way to protect young trees from egg-laying damage. Supporting your tree’s health through proper watering, mulching, and timely pruning also helps mitigate impacts.

By planning ahead and combining these strategies, you can enjoy watching nature’s incredible music-makers without sacrificing the health of your cherished trees. Remember that patience is key , once the brief emergence passes, your landscape will rebound beautifully until the next grand chorus nearly two decades later.