Are 13-Year Periodical Cicadas Harmful to Vegetable Gardens?

Periodical cicadas are among the most fascinating and widely recognized insects in North America. Known for their synchronized emergences every 13 or 17 years, these insects emerge in vast numbers, creating a spectacle that attracts both intrigue and concern. One common question among gardeners and growers is whether the 13-year periodical cicadas pose any harm to vegetable gardens. In this article, we will explore the biology of 13-year periodical cicadas, their behavior, and specifically address their impact on vegetable gardens.

Understanding 13-Year Periodical Cicadas

Periodical cicadas belong to the genus Magicicada, and their life cycle is notable for its extended subterranean development phase. The 13-year cicadas are one of the two main broods of periodical cicadas (the other being the 17-year cicadas), meaning that their nymphs spend 13 years underground feeding on root xylem fluids before emerging as adults.

These cicadas are most commonly found in the central and southern United States, where they emerge en masse every 13 years. During emergence, millions of adult cicadas simultaneously come out of the ground, molt, mate, and lay eggs within a relatively short timeframe, generally a few weeks.

Cicada Life Cycle and Behavior

The life cycle of 13-year periodical cicadas is critical to understanding their potential impact:

Nymph Stage (Underground): For 13 years, nymphs live underground feeding on sap from tree roots.
Emergence: In late spring or early summer, nymphs tunnel to the surface, molt into adults, and begin their brief above-ground life.

Mating and Egg Laying: Adult females use their ovipositors to slit small branches on trees or woody shrubs to deposit eggs.
Egg Hatching: After about six weeks, nymphs hatch and drop to the soil surface before burrowing underground to begin the cycle anew.

This synchronized mass emergence is an evolutionary adaptation believed to overwhelm predators through sheer numbers.

Do 13-Year Periodical Cicadas Damage Vegetable Gardens?

When it comes to vegetable gardens, gardeners often worry about two main potential problems:

Feeding damage by nymphs or adults
Physical damage caused by egg-laying

Feeding Habits of Cicadas

Periodical cicada nymphs feed exclusively on xylem fluids from roots of trees and woody plants. Unlike many garden pests that attack shallow roots or plant stems, cicada nymphs are specialized feeders on perennial woody plant roots , they do not feed on vegetable crops’ fibrous root systems in a manner that causes significant damage.

Adult cicadas feed by piercing plant tissues with their mouthparts to suck sap but primarily target tree branches rather than herbaceous plants like vegetables.

Egg Laying Damage

Adult female cicadas lay eggs by inserting their ovipositors into small twigs or branches of woody plants. This process creates small slits or cavities where eggs develop until hatching.

Vegetable plants generally lack woody stems suitable for egg laying because:

Most vegetables have soft, herbaceous stems that cannot support egg-laying.

Cicada females prefer hardwood trees and shrubs with mature branches for oviposition.

Therefore, egg-laying damage in vegetable gardens is rare or negligible.

Physical Impact on Vegetable Plants

Since periodical cicadas do not use herbaceous plants as hosts for egg laying nor as primary feeding targets for either nymph or adult stages, direct physical damage to vegetable garden plants is minimal to nonexistent.

In large emergence years, you might notice some adult cicadas resting on vegetable leaves or stems; however, such contact does not cause harm.

Indirect Effects of Periodical Cicadas on Gardens

Although direct harm to vegetables is unlikely, there are some indirect effects that gardeners should be aware of:

Potential Damage to Fruit Trees and Woody Landscape Plants

If your garden includes fruit trees or woody shrubs adjacent to your vegetable beds, egg-laying can cause:

Twig flagging: A condition where oviposition wounds cause small branches to wither and die.
Reduced vigor in heavily infested young trees.

This damage can be concerning if fruit trees are part of your garden ecosystem but does not translate directly into harm for vegetable crops.

Soil Disturbance from Nymph Emergence

When billions of nymphs tunnel to the surface simultaneously during emergence, they can cause some soil disturbance around plant bases. However:

This disturbance is generally minor.
It rarely impacts established vegetable plants significantly.
In fact, increased soil aeration could even temporarily benefit soil health.

Attraction of Predators

The massive abundance of cicadas can attract birds and other predators. While this may increase some disturbance as predators forage in your garden area, such effects are typically temporary and not damaging to crops.

Managing Cicada Impact in Vegetable Gardens

Given that direct harm from 13-year periodical cicadas in vegetable gardens is minimal, specific management is often unnecessary. However, for those concerned about adjacent trees or young woody plants that may suffer egg-laying damage during emergence years, consider these tips:

Protective Barriers for Young Trees

Use fine mesh netting (such as cheesecloth) over young trees during peak emergence times (typically late May through June).
Remove netting after adult emergence concludes (3 to 6 weeks).

Pruning Damaged Branches Post-Emergence

After cicada emergence finishes:

Prune out twig flagging caused by oviposition scars.
Proper pruning helps prevent secondary diseases from entering damaged tissue.

Avoidance and Planning

If possible, plan vegetable gardens away from large stands of mature hardwood trees known to host periodical cicadas.
Maintain healthy plants through proper watering and fertilization so they can better tolerate minor stresses.

No Need for Chemical Control in Vegetable Beds

Chemical pesticides targeted at controlling periodical cicadas are generally unnecessary in vegetable gardens because:

Cicadas do not feed significantly on vegetables.
Pesticides may harm beneficial insects and pollinators.
The mass emergence is short-lived (a few weeks), so impacts are temporary.

Conclusion: Are 13-Year Periodical Cicadas Harmful to Vegetable Gardens?

In summary:

No significant feeding damage occurs on vegetables due to nymphs or adults.
Egg-laying occurs only on woody plants, which most vegetable plants lack.

Physical damage to vegetables is negligible during emergence years.
Indirect impacts such as minor soil disturbance or increased bird activity may occur but do not harm crops.

Therefore, gardeners can rest assured that 13-year periodical cicadas are largely harmless to vegetable gardens. While they may pose risks to young fruit trees or ornamental shrubs nearby due to egg-laying habits, these impacts do not translate into serious threats for annual vegetable crops.

Instead of worrying about controlling periodical cicadas in the garden, gardeners can view these rare emergences as natural phenomena, unique opportunities for learning about nature’s rhythms, and focus on maintaining healthy soil and plants that thrive long after the cicada chorus has faded away.