Signs That Indicate a 13-Year Periodical Cicada Swarm is Near

Periodical cicadas are some of the most fascinating and mysterious insects in the natural world. Among these, the 13-year periodical cicadas are particularly notable for their rare and highly synchronized emergences, occurring only once every 13 years. For many people, their sudden appearance can come as a surprise or even cause concern, especially given the sheer volume of cicadas that can swarm an area. Understanding the signs that indicate a 13-year periodical cicada swarm is near can help residents, gardeners, and nature enthusiasts prepare for this natural event.

What Are 13-Year Periodical Cicadas?

Before diving into the signs of an impending swarm, it’s important to understand what 13-year periodical cicadas are. These insects belong to the genus Magicicada and are unique because they spend most of their lives underground as nymphs feeding on tree root fluids. After 13 years (sometimes 17 years for other broods), they emerge en masse to molt into adults, mate, lay eggs, and then die within a few weeks.

This highly synchronized life cycle means that large numbers of cicadas emerge simultaneously in specific geographic regions. The phenomenon is both remarkable and predictable, although it doesn’t happen every year but rather according to the brood’s cycle.

Geographic Regions Affected

The 13-year cicada broods are primarily found in parts of the eastern United States including Ohio, Indiana, Illinois, Kentucky, and southern Michigan. Different broods have slightly different ranges and emergence years. For example, Brood XIX is one of the largest 13-year broods and emerges over a wide region including parts of Indiana and Kentucky.

If you live in or near these regions, being aware of the signs that herald an upcoming emergence is especially useful.

Signs That a 13-Year Periodical Cicada Swarm Is Near

1. Increased Underground Activity

Periodical cicada nymphs live underground feeding on root xylem fluid for up to 13 years. As they approach their emergence year, they begin moving closer to the surface in search of optimal conditions to emerge.

• Root Damage: One subtle sign is increased damage to young tree roots caused by feeding nymphs as they prepare to emerge.
• Soil Displacement: Some homeowners notice unusual soil movement or small mounds near trees and shrubs where nymphs are preparing exit tunnels.
• Increased Burrowing Sounds: Although faint and difficult to detect without specialized equipment, entomologists sometimes note increased subterranean movement.

2. Change in Soil Temperature and Moisture

Emergence timing is closely tied to environmental cues:

• Soil Temperature: Cicadas typically emerge when the soil temperature reaches about 64°F (18°C) at a depth of around 8 inches. Monitoring soil temperatures during late spring can indicate when emergence might begin.
• Rainfall Patterns: Heavy rains or consistent soil moisture levels help soften the soil surface making it easier for nymphs to tunnel out. Years with early or abundant rainfall may trigger earlier emergences or more intense activity.

3. Appearance of Exuviae (Cicada Shells) Nearby

During emergence nights, nymphs crawl out of the ground and climb nearby vegetation or structures before molting into adults.

• Empty Shells on Trees: One clear sign that an emergence has started is spotting empty cicada exoskeletons attached to tree bark, fences, or plant stems.
• Early Molting Events: Even before full swarm appearances, small groups of adults may emerge in localized areas signaling a broader outbreak is imminent.

4. Increased Bird Activity

Birds feed on cicadas during emergence periods. As cicadas approach adulthood near the surface:

• Bird Foraging Behavior Changes: You might observe increased bird activity near trees with unusual numbers of birds pecking at bark or catching flying insects.
• Unusual Bird Calls: Some ornithologists report birds vocalizing more frequently when large insect prey swarms appear.

5. Heightened Male Cicada Singing

Male periodical cicadas produce loud mating calls by vibrating membranes called tymbals on their abdomens:

• First Chirps or Calls Heard: Early emergers may start calling softly just before the main swarm arrives.
• Gradual Increase in Noise Levels: Over days or weeks, the volume and frequency of mating calls increase dramatically indicating that adult populations are growing.

6. Local News and Citizen Reports

Because periodical cicada emergences are predictable events tracked by entomologists:

• Community Alerts: Many local government agencies, universities, and extension offices issue warnings or updates when broods are expected to emerge.
• Citizen Science Participation: Apps like iNaturalist allow residents to report sightings which helps map emergence progress.

Following local news or social media can provide early indications that a brood is about to arrive.

7. Vegetation Damage from Egg Laying

Female cicadas cut slits into small branches to lay eggs shortly after emerging:

• Visible Twig Dieback: Observing increased twig damage or wilting in smaller branches during late spring or early summer could mean cicadas are actively laying eggs.
• Browning Tips on Young Trees: This “flagging” effect results from egg-laying wounds and can be an indirect sign that adults are present nearby.

Preparing for a Cicada Swarm

Recognizing these signs allows homeowners and gardeners to prepare appropriately:

• Protect Young Trees and Shrubs: Use netting or tree wraps to reduce egg-laying damage.
• Delay Pruning: Avoid pruning trees until after emergence to minimize harm.
• Plan Outdoor Activities: If you prefer to avoid noisy swarms, plan outdoor work before peak emergence periods.
• Educate Family Members: Children often find cicadas fascinating but may also be frightened by their numbers; learning about them in advance helps ease concerns.

Why Understanding Cicada Emergence Matters

The mass emergence of periodical cicadas plays an important ecological role:

• They provide a massive food source for birds, mammals, reptiles, and other insects.
• Their feeding activity aerates soil and contributes nutrients when they die off.
• The synchronized timing helps protect populations from predators via sheer numbers (predator satiation).

But for humans living in affected areas, knowing when a swarm will arrive prevents panic and helps mitigate any potential impacts on gardens or outdoor spaces.

Conclusion

The return of the 13-year periodical cicada brood is a remarkable event that signals one of nature’s great cycles coming full circle. By observing subtle signs such as increased underground activity, soil temperature cues, appearance of molted shells, changes in bird behavior, early mating calls, community reports, and vegetation damage from egg laying, individuals can anticipate when these insects will soon fill the air with their distinctive chorus.

Being prepared not only helps protect your property but also allows you to appreciate this incredible natural phenomenon safely and knowledgeably. Whether you love them or find them a bit unsettling, periodical cicadas remind us just how extraordinary life cycles can be in our environment — unfolding on a timetable measured not in months or years but over more than a decade!