Are 13-Year Periodical Cicadas Dangerous to Your Garden?

Periodical cicadas are some of the most fascinating insects in the natural world. Known for their synchronized mass emergences that occur every 13 or 17 years, these cicadas capture attention with their loud choruses and sheer numbers. If you’re a gardener or someone who cares about your plants, you might be wondering: are 13-year periodical cicadas dangerous to your garden? In this article, we will explore the biology of these intriguing insects, their impact on gardens, and practical advice on how to manage them.

Understanding 13-Year Periodical Cicadas

Before diving into their impact on gardens, it’s important to understand what makes these cicadas unique.

What Are Periodical Cicadas?

Periodical cicadas belong to the genus Magicicada. Unlike annual cicadas, which appear every year, periodical cicadas spend most of their lives underground as nymphs feeding on root sap. After precisely 13 or 17 years, depending on the brood, they emerge en masse as adults to mate and lay eggs before dying off weeks later.

The 13-Year Broods

Most people are familiar with the 17-year cicada broods because they affect larger territories along the eastern United States. However, there are also smaller populations that emerge every 13 years. These 13-year broods are less widespread but still create noticeable events when they surface.

Life Cycle of 13-Year Cicadas

Nymph Stage: Underground for 13 years feeding on tree roots.
Emergence: In late spring or early summer, nymphs tunnel out and molt into adults.

Mating: Males sing loudly to attract females.
Egg Laying: Females cut slits into small branches of trees and shrubs to deposit eggs.
Death: Adults die off within a few weeks.

Egg Hatching: Eggs hatch into nymphs that drop to the ground and burrow down to start the cycle anew.

Do 13-Year Periodical Cicadas Damage Gardens?

The main concern gardeners have is whether these insects pose a threat to plants, flowers, shrubs, or trees in their garden spaces.

Feeding Behavior and Plant Damage

During their underground stage, cicada nymphs feed on sap from small roots. However:

This root feeding is generally light and does not cause significant harm to mature plants.
Most garden plants have extensive root systems that can compensate for minor feeding damage.

When adults emerge:

They do not feed on leaves or flowers like other insects.
Their primary activity is mating and egg-laying.

Egg-Laying Damage (Flagging)

The most noticeable damage caused by periodical cicadas is from females laying eggs:

Females use a sharp ovipositor (egg-laying appendage) to cut into young twigs.
This can cause twig dieback or “flagging,” where affected branches turn brown and die.
Flagging usually occurs on small diameter branches less than about half an inch thick.

How Severe Is This Damage?

For large trees: The impact is usually minimal because trees can easily replace lost growth.
For young saplings or small shrubs: Repeated cycles of egg-laying may stress or prevent growth temporarily but rarely kill the plant.
For garden plants like perennials or annual flowers: Cicadas do not feed on leaves or stems and thus cause no direct damage.

Impact Summary

Benefits of Periodical Cicadas in a Garden Ecosystem

While gardeners often worry about damage, periodical cicadas also bring ecological benefits:

Soil Aeration and Nutrient Cycling

Nymph burrowing tunnels aerate soil.

Dead adult bodies provide nutrient pulses that enrich garden soil after emergence.

Natural Pest Control

Large numbers of cicadas attract predators such as birds and small mammals.
These predators may help control other garden pests indirectly.

Pollinator Benefits

Though cicadas do not pollinate plants directly, their emergence coincides with increased bird activity that supports pollinator-friendly ecosystems.

Managing Cicada Impacts in Your Garden

If you expect a brood of 13-year periodical cicadas in your area, here are some practical tips to protect your garden without harming these fascinating insects:

Preventing Egg-Laying Damage

Cover vulnerable young trees and shrubs with fine mesh netting during peak emergence (typically late May through June).

Avoid pruning during emergence since new growth attracts females for egg-laying.

Supporting Tree Health

Water young trees thoroughly before emergence to help them withstand occasional branch flagging.
Fertilize healthy trees after cicada emergence to promote recovery from any twig loss.

Avoiding Pesticides

Insecticides are generally unnecessary and ineffective against periodical cicadas.
Pesticides can harm beneficial insects that keep other garden pests in check.

Physical Removal

Manually remove egg-laden twigs if practical during or shortly after emergence. Dispose of them away from plantings.

When Should You Be Concerned?

While periodical cicadas rarely cause serious harm to established gardens, some situations warrant caution:

Young orchard trees: Repeated egg-laying can reduce fruit yields temporarily.
Newly planted saplings: Especially susceptible due to limited root reserves.

Rare or sensitive plants: Monitor for any unusual decline during emergences.

In these cases, protective netting combined with vigilant watering and care can prevent long-term damage.

Conclusion: Should You Fear the 13-Year Cicada?

The arrival of a 13-year periodical cicada brood is an extraordinary natural event that many gardeners anticipate with curiosity rather than dread. While female cicadas do cause some minor branch damage through egg-laying, this rarely threatens the overall health of mature plants. Most gardens will experience only temporary twig flagging without lasting harm.

By understanding their life cycle and behaviors, gardeners can take simple precautions such as netting young plants and providing good cultural care during emergence periods. Embracing these incredible insects as part of your garden’s ecosystem enhances biodiversity and soil health over time.

Ultimately, the 13-year periodical cicada cycle is more a marvel than a menace—one that reminds us how interconnected our gardens truly are with the rhythms of nature. So when they arrive, prepare wisely but enjoy the spectacular chorus rather than fearing it. Your garden will thank you for it!

If you’re curious whether a brood is due in your region soon, local extension services or entomology departments often provide maps and updates on periodical cicada emergences.