Natural Methods to Control 17-Year Periodical Cicada Populations

Periodical cicadas, particularly the 17-year species (Magicicada spp.), are among nature’s most fascinating and notorious insects. Emerging in massive broods every 17 years, these cicadas capture public attention with their loud chorus, sheer numbers, and unique life cycle. While they are generally harmless to humans, their mass emergence can cause significant stress to trees and agricultural plants due to their egg-laying habits.

Controlling such massive populations can be challenging. However, natural methods offer sustainable, eco-friendly solutions that minimize environmental impact while helping to reduce cicada damage. This article explores several natural strategies for managing 17-year periodical cicada populations effectively.

Understanding the 17-Year Periodical Cicada

Before diving into control methods, it’s important to grasp the life cycle and behavior of these insects:

• Life Cycle: The nymphs live underground for 17 years, feeding on tree root xylem. After this long developmental period, they emerge simultaneously in large numbers.
• Emergence: The mass emergence occurs in late spring or early summer when soil temperatures reach about 64degF (18degC).
• Mating & Egg-Laying: Adult males sing to attract females. Females lay eggs in slits they cut into small branches and twigs, which can cause damage known as “flagging,” where branches die.
• Death Post-Mating: Adults die shortly after mating and egg-laying.

Due to their synchronized emergence, managing their population requires strategic timing and understanding of their vulnerabilities.

Natural Predators as Biological Control Agents

One of the most effective natural methods for controlling cicada populations is leveraging their natural predators. Despite their overwhelming numbers, periodical cicadas face predation from various animals that help keep their populations in check.

Birds

Birds are voracious consumers of cicadas. Species such as crows, blue jays, grackles, and mockingbirds feed heavily on both adults and nymphs. Encouraging bird activity in areas prone to cicada infestations can naturally reduce cicada numbers.

• How to encourage birds:
• Install bird feeders and birdhouses.
• Plant native shrubs and trees that provide shelter.
• Avoid pesticides that harm bird food sources.

Mammals

Small mammals like squirrels, raccoons, and opossums consume cicadas opportunistically during emergence events. They dig through soil to extract nymphs or catch adults on trees.

Insects and Arachnids

Several predatory insects also play a role:
– Spiders trap adult cicadas in webs.
– Praying mantises and robber flies prey on adults.
– Parasitic wasps lay eggs in cicada nymphs or adults.

Encouraging a healthy ecosystem with diverse insect populations supports these natural predators.

Promoting Healthy Tree Growth and Resilience

Since female cicadas target young branches for egg-laying, maintaining vigorous tree health helps reduce damage severity:

• Proper Watering: Keep trees well-watered during dry spells to help them recover from branch flagging.
• Mulching: Apply organic mulch around tree bases to retain moisture and improve soil quality.
• Pruning: Remove flagging branches promptly after emergence to prevent secondary infections and promote new growth.
• Fertilization: Use appropriate fertilizers based on soil tests to boost tree vitality before cicada emergence.

Healthy trees can better withstand the stress of egg-laying damage and recover faster afterward.

Timing Planting and Pruning Activities

Adjusting horticultural practices according to the cicada life cycle avoids unnecessary stress on vegetation:

• Avoid Pruning During Emergence: Pruning stimulates new growth that attracts female cicadas for egg-laying. Wait until after the emergence event to prune trees.
• Delay Planting Young Trees: Newly planted or young trees are more vulnerable to damage. If possible, delay planting until after the cicadas have emerged.
• Plant Cicada-Resistant Varieties: Some tree species show less susceptibility to egg-laying damage. Research your local varieties for more resilient options.

These timing strategies reduce exposure of vulnerable plant tissues during peak cicada activity.

Physical Barriers and Exclusion Techniques

Though impractical for large-scale control due to the vast numbers of cicadas, physical barriers can protect valuable individual plants or young trees:

Fine Mesh Netting

Covering smaller trees or shrubs with fine mesh netting during emergence prevents females from reaching branches to lay eggs. Use netting with mesh size smaller than 1/4 inch.

• Application tips:
• Secure netting tightly around the tree canopy.
• Remove netting promptly after the emergence period (usually 4-6 weeks).

Sticky Bands

Sticky bands wrapped around tree trunks may catch crawling nymphs as they ascend trees after emerging from the soil. However, sticky bands must be monitored regularly to avoid trapping beneficial insects or causing harm.

Encouraging Soil Health and Nematode Activity

Since nymphs spend most of their lives underground feeding on tree roots, targeting this stage can reduce adult emergence numbers:

Beneficial Nematodes

Certain species of entomopathogenic nematodes (e.g., Steinernema spp.) infect and kill soil-dwelling insect pests including cicada nymphs.

• How to use nematodes:
• Apply nematode inoculants in moist soil during late summer or early fall when nymphs are near the surface.
• Maintain adequate soil moisture for nematode survival.

While not able to eradicate entire broods alone, nematode applications contribute as part of integrated pest management.

Composting and Soil Amendments

Healthy organic soils support beneficial microorganisms and predators that may naturally suppress cicada nymph populations by creating unfavorable conditions underground.

Leveraging Cicada Life Cycle Characteristics

Cicadas have evolved a remarkably synchronized life cycle that ironically presents opportunities for control:

Target Narrow Emergence Windows

Since all individuals emerge within a short time frame every 17 years:
– Focus control efforts intensively during this limited period.
– Deploy physical barriers or encourage predator activity precisely when adults emerge above ground.

Disrupt Mating Signals Using Noise or Light?

Though largely experimental:
– Some studies investigate using loud noises or lights to disrupt male mating calls temporarily.
– This method is not yet practical on large scales but could complement other controls in localized areas.

Avoid Chemical Pesticides When Possible

Chemical insecticides often have limited effectiveness due to sheer numbers of cicadas emerging simultaneously. Furthermore:

• Pesticides can harm beneficial predators like birds, spiders, and beneficial insects.
• Broad pesticide use disrupts ecosystem balance leading to secondary problems.

Natural methods combined with habitat management provide safer long-term solutions than chemical controls for periodical cicadas.

Conclusion

Managing 17-year periodical cicada populations requires understanding their unique biology and leveraging nature’s own control mechanisms. By encouraging predators like birds and beneficial insects, promoting healthy tree growth, using physical barriers thoughtfully, improving soil health with nematodes and organic amendments, and timing horticultural practices appropriately, you can reduce cicada damage sustainably.

While complete eradication may be impossible given their incredible numbers and synchronized emergences, these natural approaches minimize harm to plants without disrupting broader ecosystems. Preparing ahead of the next brood appearance will ensure your landscape weathers the event gracefully, protecting both your trees and the delicate balance of nature’s cycles.

Embrace these natural strategies as part of an integrated plan for healthy gardens and landscapes resilient against the awe-inspiring spectacle of periodical cicadas.