Where 13-Year Periodical Cicadas Lay Eggs: Key Locations to Monitor

Periodical cicadas are one of nature’s most fascinating phenomena, captivating scientists and enthusiasts alike with their synchronized emergences every 13 or 17 years. Among these, the 13-year periodical cicadas stand out due to their highly predictable life cycle and remarkable impact on their habitats. A critical aspect of understanding and monitoring these insects involves identifying where they lay their eggs. This article explores the key locations where 13-year periodical cicadas deposit their eggs, why these sites matter, and how monitoring them can help in ecological research and management.

Introduction to 13-Year Periodical Cicadas

Periodical cicadas belong to the genus Magicicada. Unlike annual cicadas, which appear every year, periodical cicadas spend almost their entire lives underground as nymphs feeding on tree root sap. The 13-year species emerge en masse after precisely 13 years, mate vigorously during a few weeks of the late spring or early summer, and then die shortly after.

The emergent adult females lay eggs into small branches or twigs of trees and woody shrubs. These egg-laying activities are not random; they influence forest ecology, affect tree health, and even provide food for various predators.

Why Study Cicada Egg-Laying Locations?

Understanding where 13-year periodical cicadas lay their eggs is crucial for several reasons:

Ecological Impact: Egg-laying causes damage known as “flagging” , where branch tips wilt and die. Monitoring egg-laying sites helps gauge potential impacts on local vegetation.
Population Tracking: Knowing the preferred oviposition (egg-laying) sites allows researchers to track population density and distribution.

Pest Management: Though cicadas are not typically considered pests, heavy infestations can stress young trees in orchards or nurseries; thus, monitoring helps manage risks.
Scientific Research: Insight into oviposition preferences aids studies of cicada behavior and habitat requirements.

Key Characteristics of Egg-Laying Behavior

Before diving into specific locations, it’s important to understand some basics of how female 13-year periodical cicadas lay eggs:

Females use a specialized ovipositor to cut slits into small twigs or branches.
Eggs are deposited in these slits in rows.
Preferred branches are typically about pencil-thick or thinner.

Egg-laying tends to occur on deciduous trees but varies based on local species availability.
Damage from egg-laying often results in distinctive browning or “flagging” of branch tips.

Primary Locations Where 13-Year Periodical Cicadas Lay Eggs

1. Small Branches and Twigs of Deciduous Trees

Most commonly, female cicadas choose small terminal branches approximately 3-7 mm in diameter. These are young shoots that provide easier access for the ovipositor.

Common Tree Hosts:

Oak Trees (Quercus spp.)
Oaks are a favorite host for 13-year periodical cicadas. They offer abundant twigs suitable for egg deposition. Flagging is often visible on oak branches following emergence years.
Maple Trees (Acer spp.)
Maples also serve as frequent oviposition sites due to their widespread presence and suitable twig size.
Hickory Trees (Carya spp.)
Hickories provide strong support but still produce twigs ideal for egg laying.

Elm Trees (Ulmus spp.)
Elms are commonly used in some regions, though preference varies geographically.

Female cicadas carefully select twigs that balance ease of cutting with sufficient tissue to support eggs until they hatch.

2. Woody Shrubs and Smaller Trees

In some habitats where larger trees are scarce, cicadas will lay eggs in shrubs or small understory trees:

Dogwood (Cornus spp.)
Dogwoods’ slender branches make them susceptible hosts.

Sumac (Rhus spp.)
Sumacs’ dense shrubbery offers ample twig sites.

Monitoring these plants can reveal egg presence even when larger tree hosts are less common.

3. Young Saplings and Nursery Plants

Young trees growing in nurseries or plantations are especially vulnerable because of thinner branches:

Orchards with young fruit trees such as cherries or plums may experience cicada egg-laying damage.
Seedlings often show pronounced flagging after an emergence event.

This makes nursery managers an important group interested in identifying and monitoring oviposition sites.

4. Edge Habitats and Forest Margins

Cicadas often prefer edge habitats , places where forest meets open fields or roadsides:

Twigs at edges receive more sunlight, possibly influencing female choice.

Higher densities often occur at these transitional zones due to tree species diversity.

Monitoring should target these ecotones for early detection of oviposition activity during emergence years.

How to Identify Cicada Egg-Laying Sites

Recognizing egg-laying marks is vital for effective monitoring:

Look for rows of small slits cut into twigs by the female’s ovipositor.
Branch tips with wilting leaves (“flagging”) during summer can indicate recent egg deposition.
After hatching (several weeks post egg-laying), look for tiny exit holes from nymphs leaving twigs.

Using binoculars can help detect damage high in tree canopies; close inspection below is necessary for detailed examination.

Seasonal Timing for Monitoring

Females begin laying eggs shortly after adults emerge , typically late May through June in many parts of the U.S. Monitoring efforts should commence immediately upon adult emergence detection and continue through the oviposition window (approximately three weeks).

Early detection allows researchers to estimate the extent of egg deposition and plan follow-up studies or mitigation actions if needed.

Implications for Forest Health and Wildlife

Egg-laying activities impact ecosystems beyond just branch damage:

Increased twig flagging reduces photosynthetic capacity temporarily but usually does not kill mature trees.
Dead branches provide habitat niches for certain insects and fungi.

Cicada emergences provide a substantial food source for birds, mammals, reptiles, and other insects attracted to ovipositing females or freshly emerged nymphs.

Therefore, understanding where females lay eggs helps predict broader ecological consequences of a periodical cicada emergence event.

Monitoring Techniques

Visual Surveys

Walking transects through suspected habitats during emergence years allows observers to note flagged branches and confirm egg slits visually.

Photographic Documentation

Close-up photos help verify identification of egg scars while creating records useful for longitudinal studies.

Sampling Branches

Cutting a sample of twigs with suspected egg slits back to laboratories confirms presence by microscopic examination or rearing nymphs if possible.

Citizen Science Involvement

Engaging local communities through citizen science platforms encourages widespread reporting of egg-laying signs, enriching data coverage over large areas.

Conclusion

The precise knowledge of where 13-year periodical cicadas lay their eggs is essential for understanding their biology, managing potential impacts on forestry and horticulture, and appreciating their role within ecosystems. Female cicadas predominantly target small branches and twigs on deciduous trees such as oaks, maples, hickories, and elms but will also use shrubs and young saplings depending on habitat availability.

Monitoring key oviposition sites during emergence years provides valuable data that informs ecological research, biodiversity conservation efforts, pest management strategies in nurseries or orchards, and public awareness about these remarkable insects. As we anticipate future emergences of the 13-year Magicicada broods, continued observation focusing on where they lay eggs will remain a cornerstone activity for entomologists and naturalists alike.

By observing the tiny scars left behind by these elusive insects on tree branches across our woodlands each emergence year, we maintain a vital connection with one of nature’s most extraordinary cycles, a testament to the intricate rhythms shaping our environment over decades.