Do 17-Year Periodical Cicadas Affect Backyard Vegetables?

Every 17 years, some regions of the United States witness a spectacular natural event: the emergence of periodical cicadas. These insects appear in massive numbers, often surprising people who have never seen such a swarm before. For gardeners and homeowners with backyard vegetable patches, the sudden arrival of cicadas raises an important question: Do 17-year periodical cicadas affect backyard vegetables?

In this article, we will explore what periodical cicadas are, their lifecycle, their behavior around plants, and specifically how they interact with vegetable gardens. We will also discuss practical steps gardeners can take to protect their crops during cicada emergences.

What Are 17-Year Periodical Cicadas?

Periodical cicadas are a unique species (or group of closely related species) that spend most of their lives underground as nymphs feeding on tree root fluids. The most famous aspect of their life cycle is their synchronized emergence every 13 or 17 years in massive broods.

17-year cicadas emerge every seventeen years from the soil.
They surface in vast numbers to mate, lay eggs, and then die off within about a month.
The emergence is synchronized, meaning all nymphs from a brood come out nearly simultaneously.

These large insects have distinctive red eyes and black bodies with orange wing veins. While alarming in appearance and swarm size, they are generally harmless to humans.

Lifecycle and Behavior Relevant to Gardening

Underground Nymph Stage

For the first 13 to 17 years of their life, these cicadas live underground as nymphs, feeding off xylem fluids from tree roots. While this feeding may sound concerning, it usually has minimal impact on trees or other plants because:

They feed slowly on root fluids.
Their population density underground is spread out.
Most healthy trees and plants tolerate this without harm.

Vegetables in a typical backyard garden tend to have much smaller root systems compared to mature trees, and are unlikely to be significantly affected by this subterranean feeding.

Above-Ground Adult Stage

When nymphs emerge:

They crawl up tree trunks or other vertical surfaces and molt into adults.

Adult males sing loudly to attract females.
Females lay eggs by slicing slits into tree branches or stems.
Eggs hatch after several weeks; young nymphs drop to the ground and burrow in for another cycle.

The egg-laying process can cause some damage, especially if there are many females laying eggs on small branches or tender shoots.

Do Cicadas Harm Backyard Vegetables?

Feeding Damage

Unlike many garden pests such as aphids or beetles, adult periodical cicadas do not feed on leaves or fruits. They primarily use their mouthparts for mating-related activities rather than feeding on vegetable crops.

The underground nymphs feed on roots but target mostly larger woody roots rather than the fibrous roots of vegetables. Given vegetables’ short growth cycles and less extensive root systems compared to trees, cicada root feeding typically does not cause noticeable harm.

Egg-Laying Damage

The primary damage from adult cicadas occurs during egg-laying:

Females cut slits in thin branches and stems to deposit their eggs.

This “flagging” effect causes small twigs to wilt and die off.
Heavy egg-laying can stress young trees or shrubs by breaking multiple branches.

For vegetable plants:

Most vegetable stems are herbaceous and softer than woody branches.

Cicadas rarely use soft herbaceous stems for egg-laying since these plants often do not provide the structural support needed for egg nests.
However, some vine crops like tomatoes or beans with sturdy stems could potentially experience minor twig damage if heavily infested.

Overall, backyard vegetables rarely suffer significant damage from cicada egg-laying.

Indirect Effects

There can be some indirect consequences worth noting:

Physical disturbance: Large numbers of emerging cicadas may physically cover plants temporarily but don’t feed on them.
Attracting predators: Birds and small mammals attracted to cicadas might cause incidental damage while foraging.
Stress on young trees or perennials near the garden: This stress could indirectly impact garden microclimate or pest resistance.

What Does Research Say?

Studies by entomologists consistently find that periodical cicadas pose little threat to annual vegetable crops. Most documented damage occurs in young trees or woody ornamentals rather than food gardens.

A report from university extension services typically states:

Cicada nymphs do not significantly damage roots of herbaceous vegetables.
Adult egg-laying may cause minor branch dieback in woody plants but is rarely harmful enough to reduce fruit yield noticeably.

No preventative insecticides are recommended for vegetable gardens during cicada emergences since cicadas are not pests of these crops.

Tips for Protecting Your Vegetable Garden During Cicada Emergence

Though the risk is low, gardeners can take some simple steps to minimize any potential issues during heavy cicada emergences:

1. Use Physical Barriers

Cover vulnerable seedlings or young plants with fine netting or row covers until adults have finished laying eggs (usually a few weeks). This protects against physical damage from egg-laying females.

2. Support Vine Crops

Provide sturdy stakes or cages for tomatoes, beans, and other vine crops so they resist any twig breakage caused by cicada activity.

3. Water and Fertilize Appropriately

Healthy plants recover more quickly from minor injury. Keep your vegetables well-watered and fertilized during emergence periods.

4. Avoid Excessive Pruning Pre-Emergence

Don’t prune woody perennials just before cicada emergence since fresh growth is most vulnerable to egg-laying damage.

5. Clean Up Fallen Branches

Remove any twigs flagged by female egg-laying promptly to reduce stress on nearby plants and minimize habitat for pests attracted to dead material.

Conclusion: Should You Worry About Cicadas in Your Vegetable Garden?

The arrival of 17-year periodical cicadas can be startling due to their sheer numbers and loud chorus, but they generally do not pose a serious threat to backyard vegetable gardens.

While adult females do cause minor branch dieback when laying eggs, especially in woody plants, most vegetable crops experience little or no harm from either root-feeding nymphs or adults.

By employing basic protective measures such as covers for young seedlings during peak emergence weeks, maintaining good plant health, and supporting vulnerable vine crops, gardeners can effectively safeguard their backyard veggies with minimal effort.

In short: enjoy this rare natural spectacle without fear it will ruin your homegrown tomatoes or beans!

References available upon request.