Best Practices for Managing 17-Year Periodical Cicada Infestations

Every 17 years, a unique and fascinating natural phenomenon occurs in parts of North America: the emergence of periodical cicadas. These insects, belonging to the genus Magicicada, spend most of their lives underground as nymphs before emerging en masse to molt, mate, and lay eggs. While they don’t bite or sting, their overwhelming numbers and the damage they can cause to young trees and shrubs often make them a concern for homeowners, gardeners, and farmers alike.

Managing 17-year periodical cicada infestations requires a strategic approach grounded in understanding their biology, timing interventions appropriately, and using environmentally responsible control methods. This comprehensive guide will explore best practices to handle these periodic invasions effectively.

Understanding 17-Year Periodical Cicadas

Before diving into management techniques, it’s essential to understand the life cycle and behavior of these cicadas:

Life Cycle: These cicadas spend 17 years underground as nymphs feeding on root sap. After this prolonged development period, they emerge synchronously in massive numbers, usually during late spring.
Emergence Behavior: Once above ground, cicadas molt into adults over several days. Males then sing loudly to attract females. After mating, females lay eggs in small twigs and branches.
Damage Potential: The main damage occurs when females cut slits in small tree branches to deposit eggs. This can cause “flagging,” where twig tips dry out and die. Heavy infestations can weaken young trees and shrubs.

Natural Control: Periodical cicadas are prey for various birds, mammals, reptiles, and even other insects. Their overwhelming numbers ensure that many survive to reproduce despite predation.

Understanding the timing and nature of their emergence is key to effective management.

Best Practices for Managing Cicada Infestations

1. Monitor Cicada Emergence Timings

The first step is predicting when the cicadas will emerge in your area:

Identify Brood Patterns: Periodical cicadas are grouped into broods that emerge on different schedules and regions. Knowing which brood appears locally helps anticipate emergences.

Use Historical Records & Maps: Local extension offices or universities often publish maps and schedules for upcoming cicada emergences.
Start Monitoring Early Spring: Look for signs such as nymphs tunneling out of soil or discarded exoskeletons attached to trees.

Early detection allows you to prepare for potential impacts on your landscape or crops.

2. Protect Young Trees and Landscaping

Young trees (typically less than 3 years old) are most vulnerable to branch damage from egg-laying females. Protect them by:

Physical Barriers: Use fine mesh netting (less than 1/4 inch) or floating row covers over susceptible plants during peak emergence (usually 4-6 weeks).
Timing Application: Install netting just before peak emergence and leave it until all adults have died off (about a month).
Pruning Damaged Branches: Remove twig tips showing flagging after emergence to prevent secondary infections or pest issues.

For mature trees, damage is generally cosmetic and does not require intervention.

3. Avoid Unnecessary Pesticide Use

Due to their role in ecosystems and lack of direct harm to humans or pets, widespread pesticide application is not recommended:

Limited Efficacy: Cicadas emerge in large numbers but live only a few weeks above ground. Pesticides often provide minimal long-term control.
Environmental Impact: Broad-spectrum insecticides can harm beneficial insects like bees and natural predators.

Selective Use: If absolutely necessary (e.g., commercial orchards with high-value crops), use targeted insecticides labeled for cicada control early in the emergence when nymphs are vulnerable near soil surface.

Always follow local regulations and integrated pest management principles when considering chemical control.

4. Encourage Natural Predators

Natural predators play a significant role in controlling cicada populations:

Bird Habitats: Encourage birds by providing feeders, birdhouses, and water sources.

Beneficial Insects: Maintain diverse plantings that support predatory insects like wasps and spiders.

While natural predation won’t prevent mass emergences, it can reduce adult populations somewhat and help maintain ecological balance.

5. Lawn and Garden Maintenance

Good cultural practices can minimize cicada damage:

Watering & Fertilizing: Healthy plants recover better from minor damage caused by egg-laying or feeding.

Mulching: Mulch around trees helps retain moisture but avoid thick layers that might impede nymph emergence monitoring.
Soil Aeration: Aerating turf may help disrupt nymph tunnels without significant harm but should be done carefully during non-emergence years.

6. Dispose of Dead Cicadas Properly

Post-emergence cleanup reduces nuisance issues:

Raking & Removing Shells: Remove molted exoskeletons if desired; these do no harm but some find them unsightly.
Composting Considerations: Dead cicadas can be composted but be aware they decompose slowly due to their chitinous exoskeletons.

Avoid Burning Piles: Do not burn dead cicadas as this releases unpleasant odors and toxins.

7. Implement Long-Term Planning

Since these events occur every 17 years, long-term planning minimizes disruption:

Plant Selection: Favor mature trees less affected by egg-laying damage or species less attractive to cicadas such as pines or maples over susceptible fruit trees.
Brood Awareness in Landscaping Decisions: Coordinate planting schedules so young saplings are not present during expected emergences if possible.
Community Cooperation: Engage neighbors for coordinated management efforts since periodical cicadas move freely across properties.

Addressing Common Questions About Cicada Management

Q: Are periodical cicadas harmful to people?
A: No. They do not bite or sting humans or pets. Their main impact is physical damage to small branches during egg-laying.

Q: Will cicadas kill my trees?
A: Mature healthy trees usually tolerate egg-laying damage with no long-term effects. Young saplings may suffer branch dieback but generally survive with proper care.

Q: Can I use traps or baits?
A: There are no effective commercial traps or baits specifically for periodical cicadas due to their brief adult lifespan and mass emergence strategy.

Q: How long do adult cicadas live?
A: Adults typically live about 4 to 6 weeks above ground before dying after reproduction.

Conclusion

Managing 17-year periodical cicada infestations hinges on knowledge, preparation, and environmentally responsible strategies rather than attempting eradication, since these insects are a natural part of many ecosystems. By monitoring brood cycles, protecting vulnerable young plants with physical barriers, avoiding unnecessary pesticides, promoting natural predators, maintaining plant health, preparing for future emergences through thoughtful landscaping choices, and cooperating with local communities, homeowners and land managers can effectively navigate these fascinating yet challenging natural events with minimal damage or disruption.

Embracing these best practices ensures coexistence with one of nature’s most extraordinary insect spectacles while maintaining healthy landscapes year-round.