Signs of 13-Year Periodical Cicada Damage to Young Trees

Periodical cicadas are remarkable insects known for their unique life cycles, emerging in massive broods every 13 or 17 years. Among these, the 13-year periodical cicadas are particularly notable in certain regions of the United States. While their synchronized emergence is a fascinating natural phenomenon, it can cause significant damage to young trees and shrubs. Understanding the signs of 13-year periodical cicada damage is essential for gardeners, arborists, and landowners to protect vulnerable plants during these outbreaks.

Understanding 13-Year Periodical Cicadas

Periodical cicadas belong to the genus Magicicada and have one of the longest and most synchronized life cycles among insects. They spend the majority of their lives underground as nymphs, feeding on sap from tree roots. After 13 years, they emerge simultaneously in large numbers to mate, lay eggs, and then die within a few weeks.

The adult cicadas cause damage primarily through their egg-laying behavior. Females use a saw-like ovipositor to cut slits into small branches where they deposit eggs. This process, known as “flagging,” can lead to branch dieback, reduced growth, and sometimes death of young or weak trees.

Why Are Young Trees More Vulnerable?

Young trees are particularly susceptible to cicada damage because:

• Their branches are thinner and more fragile.
• They have less established root systems to recover from stress.
• Damage to their growing tips can stunt growth or deform the tree structure.
• They may have fewer reserves to survive extensive branch damage.

Older, mature trees tend to tolerate cicada activity better, although severe infestations can still cause stress and minor damage.

Identifying Cicada Damage: Key Signs on Young Trees

1. Flagging of Small Branches

The most distinctive sign of cicada damage is “flagging,” where twigs or small branches suddenly wither and turn brown while still attached to the tree.

What Causes Flagging?
Females cut slits into branches with their ovipositor to lay eggs. These cuts disrupt the vascular tissue and introduce wounds that impair water and nutrient flow. As a result, affected branches die back beyond the egg-laying site.

How to Spot It:
– Look for clusters of thin branches that appear dried out or wilted.
– Flagged branches often resemble “flags” sticking out from healthy green foliage.
– This symptom typically appears within weeks after cicada emergence.

2. Scars or Slits on Branches

Examining young branches closely will reveal small cuts or scars arranged in series along stems.

Details:
– The scars are narrow, roughly oval-shaped slits about 1/4 inch long.
– They appear in rows where females have laid multiple eggs.
– The bark around these slits might be slightly raised or cracked.

3. Wilting and Leaf Browning

Branches with egg-laying damage may exhibit:

• Wilting leaves that fail to perk up even with adequate watering.
• Leaves turning yellow or brown prematurely.
• Reduced leaf size or distorted shapes caused by stress.

In young trees, this leaf damage can significantly reduce photosynthesis and stunt growth.

4. Reduced Growth

Damage to terminal buds or growing tips affects new shoot development.

Signs include:

• Shortened shoots with fewer leaves.
• Twisted or malformed growth patterns.
• Delayed leaf emergence in the spring following an outbreak.

If many growing tips are lost, overall tree height and canopy spread may be limited for several years until recovery occurs.

5. Branch Dieback

In severe infestations, entire limbs may die back from repeated cicada injury compounded by secondary pathogens entering through wounds.

Watch for:

• Larger sections of dead wood extending from flagged areas.
• Increased brittleness when branches break easily.
• The presence of fungal fruiting bodies or discoloration near wounds signaling infection.

6. Presence of Cicadas

Seeing adult cicadas around your trees during their emergence period (usually late spring to early summer) strongly indicates potential damage risk.

Look for:

• Large numbers of noisy cicadas on trunks and branches.
• Exuviae (cast skins) clinging to bark after nymphs molt.
• Eggs deposited visibly under the bark if you peel back damaged twigs carefully.

Consequences of Cicada Damage on Young Trees

When left unmanaged, periodical cicada outbreaks can lead to several negative outcomes for young trees:

• Structural Weakness: Repeated loss of growing tips causes trees to develop multiple competing leaders or crooked branches susceptible to breakage.
• Reduced Vigor: Loss of foliage and branch dieback lowers photosynthetic capacity, reducing energy reserves needed for growth and defense against pests.
• Increased Susceptibility: Open wounds from oviposition cuts invite fungal infections like canker diseases that further weaken trees.
• Mortality Risk: In extreme cases where most branch tips are destroyed repeatedly over successive brood emergences, young saplings may not survive.

Differentiating Cicada Damage from Other Tree Problems

Young trees exhibit stress symptoms from various causes such as insect borers, drought, disease, or mechanical injury. Here’s how cicada damage stands out:

Protecting Young Trees from Cicada Damage

While it’s impossible to prevent all cicada activity during a brood emergence year due to their sheer numbers, taking precautions can mitigate damage:

Physical Barriers

Cover small trees with fine mesh netting or floating row covers starting before cicadas emerge (early May) and keep in place until mid-July once egg laying ceases.

Pruning Practices

After emergence:

• Remove flagged twigs promptly by cutting back several inches below damaged areas.
• Disinfect pruning tools between cuts to avoid spreading pathogens.

Pruning encourages healing and reduces pathogen entry points.

Tree Health Maintenance

A healthy tree withstands stress better:

• Water consistently during dry spells.
• Apply mulch around base but avoid piling against trunk.
• Fertilize appropriately based on soil tests to promote vigorous growth pre- and post-emergence years.

Avoid Planting New Saplings in High-Risk Areas

If you live in a region expecting a brood emergence soon (consult local extension offices), consider delaying new tree planting until after the brood has emerged to reduce vulnerability.

Conclusion

The 13-year periodical cicadas create an extraordinary natural spectacle but pose significant challenges for young tree health through their egg-laying behavior. Recognizing signs such as flagging branches, oviposition scars, wilting leaves, and reduced growth allows timely intervention to protect valuable saplings. Proper management combining physical protection, pruning care, and maintaining overall tree vigor can minimize long-term consequences. With informed vigilance during cicada emergence years, young trees have a better chance of surviving these cyclic invasions intact , ready to grow strong until next time nature calls them forth again.