What Are Cicadas? Everything You Need to Know About Their Swarms and Life Cycle

Observe nature’s grand emergence and learn eco-friendly ways to safeguard young saplings.

By Medha deb

Created on Sep 25, 2025

Observe nature’s grand emergence and learn eco-friendly ways to safeguard young saplings.

What Is a Cicada?

Cicadas are large, unique insects recognized for their stout bodies, broad heads, clear-membrane wings, and prominent compound eyes. With over 3,000 species worldwide, cicadas play a fascinating role in ecosystems and stand out for their distinct sound and remarkable emergence cycles. While some cicadas appear every year (annual cicadas), others—known as periodical cicadas—emerge only once every 13 or 17 years, forming vast swarms that captivate scientists and the public alike.

Types of Cicadas: Annual vs. Periodical

Annual cicadas: Emerge every summer and are commonly seen across many regions.
Periodical cicadas: Have extraordinary synchronized life cycles, spending most of their lives underground and reemerging in massive numbers every 13 or 17 years, depending on the species.

Both types share similar appearances, with black bodies and wings marked by orange veins. Periodical cicadas, in particular, are renowned for their spectacle of synchronized emergence, which only lasts for about two months.

Cicada Life Cycle: Underground and Above

The life of a cicada is divided into two stages: an underground nymphal stage and a brief, active adulthood aboveground. Here’s how their life unfolds:

After hatching, nymphs burrow underground where they feed on plant root sap for years.
Annual nymphs emerge after 2 to 5 years, but generations overlap so some appear each summer. Periodical nymphs remain underground for either 13 or 17 years before surfacing as adults.
Upon emerging, nymphs climb nearby trees or structures and molt, leaving behind brown husks (exoskeletons), which can be found scattered on trees, fences, and walls.
Adults then mate, lay eggs in small tree branches, and die soon after, completing the cycle.

Why Do Cicadas Swarm in Such Huge Numbers?

The synchronized swarming behavior of periodical cicadas is one of nature’s most impressive events. Scientists theorize that this mass emergence is an evolutionary survival strategy: by appearing in overwhelming numbers, cicadas ensure that enough of their population survives predation to continue the species. While predators feast, there are simply too many cicadas for them to consume them all.

What to Expect During a Cicada Emergence

Loud sounds: Adult males produce one of the loudest insect noises in North America. These mating calls can reach up to 100 decibels and persist from dawn to dusk.
Molted exoskeletons: As nymphs become adults, they leave behind cast skins that litter outdoor surfaces and plants.
Sudden appearance: For a few weeks, cicadas are everywhere—in trees, on lawns, garden fences, and even on your car.

Though their presence can be unnerving, cicada emergences are brief and harmless.

Are Cicadas Dangerous to Humans, Pets, or Gardens?

Cicadas
do not bite or sting and pose little threat to humans, pets, homes, veggies, or flowers:

No biting or stinging: Their mouths are adapted for drinking plant sap but can’t bite or sting humans or pets.
Not poisonous: They are not venomous and do not transmit diseases.
Safe if accidentally eaten by pets: If a dog or cat eats a few, it may get an upset stomach, but there’s no need for concern.
Harmless to established trees and plants: Cicadas drink small amounts of sap but don’t defoliate leaves or eat fruits/vegetables.
Youthful trees at risk: Small, newly planted trees, especially those with thin trunks, can suffer damage from egg-laying slits, so take precautions to cover them.

Benefits of Cicadas for the Environment

Food source: Birds, mammals, reptiles, and other insects feast on cicadas during swarms.
Soil aeration: Cicada tunnels help water penetrate and aerate the ground.
Soil fertilization: After death, cicada bodies decompose, adding nutrients to the soil.

In many cultures and food traditions, cicadas are even consumed as a novelty or delicacy.

How to Protect Your Property From Cicadas

You might not welcome cicadas into your garden, but here are science-backed ways to manage their presence without harming the environment or beneficial insects:

Problem	Solution
Damage to young trees	Use mesh or netting with ¼-inch or smaller openings to protect trunks and branches. Delay planting new trees or shrubs until fall, if possible.
Cicadas on established plants	No significant precautions necessary; established trees are not at risk.
Cicadas indoors	Keep windows and doors closed. If one enters, gently trap it in a container and release it outside.

Avoid pesticides: Spraying for cicadas is not effective and may harm other wildlife, pets, and even children. Pesticides won’t keep them away, and many more will arrive regardless.

What Not to Do When Cicadas Arrive

Don’t use chemical sprays: Treating yards with pesticides puts pollinators, birds, and pets at risk and offers little to no protection.
Don’t try to eliminate them all: Cicada swarms are brief and removing them is usually futile. Witnessing their emergence is an amazing natural event.
Don’t panic: Their presence is temporary, and cicadas do not cause long-term damage to landscapes or structures.

Expert Tips to Prepare for Cicada Swarms

Protect newly planted trees: Use fine mesh or cheesecloth around trunks and branches to prevent nymphs from climbing up.
Delay landscaping projects: If you haven’t yet planted shrubs or trees, wait until fall after the emergence has passed.
Clean up debris: Remove exoskeletons and adult carcasses from patios and walkways as needed.
Educate children and pets: Remind them to avoid handling cicadas, though they pose no real threat.

Frequently Asked Questions About Cicadas

Q: What should I do if a cicada gets inside my house?

Use a cup or container to gently capture the cicada and release it outside. Avoid direct handling, as cicadas have piercing-sucking mouthparts for drinking sap and could pierce skin by accident, though they are not dangerous.

Q: Why are the males so loud?

Males produce mating calls to attract females using a special organ called a tymbal. These calls are harmless but can reach very high volumes when thousands sing in unison.

Q: How long will the cicadas be out?

Cicada swarms last about two months. After mating and laying eggs, the adults die off and their offspring begin the next cycle underground.

Q: Can cicadas harm my vegetable or flower garden?

No. Adult cicadas do not feed on garden produce, flowers, or leaves. Their feeding is limited to small amounts of sap from woody plants.

Q: Are cicadas harmful to pets?

No, but eating many at once may cause your pet to have an upset stomach. Cicadas are not toxic nor do they transmit diseases.

Final Thoughts: Why You Should Welcome Cicadas

The mass emergence of periodical cicadas is an amazing natural phenomenon. While their sounds and sheer numbers can be overwhelming, cicadas are harmless, ecologically beneficial, and only stick around briefly. By preparing thoughtfully and avoiding pesticides, you can protect your young trees, help local wildlife, and participate in a rare event—one that future generations will also cherish.

Understanding cicadas—how they live, why they swarm, and the safest, most eco-friendly ways to manage their arrival—is key for any homeowner or gardener caught in the midst of a cicada emergence.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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