The Buzz is Back: Mapping Cicada Emergence in Tennessee 2021

In the spring of 2021, Tennessee, along with several other states across the eastern United States, experienced a phenomenon that only occurs every 13 or 17 years: the emergence of periodical cicadas. This year, it was Brood X, one of the largest and most widespread of the 17-year cicada broods, that took center stage, creating a cacophony of buzzing that both fascinated and frustrated residents. While the peak emergence is now a memory, understanding the 2021 cicada map in Tennessee remains valuable for future predictions and appreciating the complex life cycle of these fascinating insects.

The Great Cicada Spectacle: Brood X Arrives

The emergence of Brood X in 2021 was a significant event, both ecologically and culturally. These periodical cicadas, belonging to the genus Magicicada, spend the vast majority of their lives as nymphs underground, feeding on the sap of tree roots. After 17 years, they emerge en masse, triggering a biological clock honed by evolution. This synchronized emergence overwhelms predators, ensuring the survival of a significant portion of the population.

The sheer volume of cicadas is what makes the event so memorable. Millions, even billions, can emerge in a relatively small area, creating a deafening chorus as males call out to attract mates. While the noise can be disruptive, it’s a testament to the power of nature and a fascinating display of insect behavior.

Mapping the Buzz: Understanding Cicada Distribution in Tennessee 2021

While Brood X’s emergence was widespread across the eastern US, the intensity and distribution varied from region to region. Creating a "cicada map" for Tennessee in 2021 involved gathering data from various sources, including citizen science observations, academic research, and anecdotal reports. While a precise, real-time map is difficult to achieve, the available data paints a clear picture of where the cicadas were most prevalent in the state.

Key Factors Influencing Cicada Distribution:

Several factors contribute to the uneven distribution of cicadas within Tennessee. These include:

Forest Cover and Tree Density: Cicadas rely on trees for both food (as nymphs) and mating (as adults). Areas with mature forests and high tree density generally experience higher cicada populations. Brood X tends to be more abundant in areas with oak and hickory trees, which are common in Tennessee’s forests.
Soil Type: The type of soil can influence the success of cicada nymphs. Well-drained soils are generally preferred, as they allow for easier burrowing and movement. Heavy clay soils can be less hospitable.
Past Land Use: Areas that have been recently cleared or heavily developed may have lower cicada populations, as the disruption can impact the nymphs underground. Conversely, areas with long-established forests are more likely to support thriving cicada colonies.
Historical Emergence Patterns: Cicada broods tend to emerge in areas where they have emerged historically. While there can be some shifts in distribution over time, the basic pattern often remains consistent.

Regional Breakdown of Cicada Activity in Tennessee:

Based on observations and reports from 2021, here’s a general overview of cicada activity across different regions of Tennessee:

East Tennessee: This region, characterized by the Appalachian Mountains and extensive forests, saw significant Brood X activity. Counties like Knox, Blount, and Sevier experienced heavy emergences, with noticeable noise levels and numerous cicadas observed in both urban and rural areas. The presence of mature oak and hickory forests in the Great Smoky Mountains National Park and surrounding areas likely contributed to the high cicada populations.
Middle Tennessee: Middle Tennessee also experienced a widespread emergence of Brood X. Counties such as Davidson, Williamson, and Rutherford reported significant cicada activity, particularly in areas with mature trees and established neighborhoods. The relatively mild climate and fertile soils of this region are conducive to cicada survival.
West Tennessee: While Brood X was present in West Tennessee, the emergence was generally less intense compared to the eastern and middle regions of the state. Counties like Shelby, Madison, and Hardeman reported cicada activity, but the overall density was lower. This could be due to a combination of factors, including variations in forest cover and soil type. The Mississippi River Delta region, with its unique ecological characteristics, may not be as ideal for Brood X as other parts of Tennessee.

Citizen Science and Mapping Efforts:

The creation of a cicada map relies heavily on citizen science initiatives. Websites like Cicada Mania and iNaturalist allow individuals to report cicada sightings and contribute to a broader understanding of cicada distribution. In 2021, thousands of Tennesseans participated in these efforts, providing valuable data that helped to refine the map. These reports included location data, photographs, and descriptions of cicada behavior, offering a detailed snapshot of the emergence across the state.

Beyond the Map: Ecological Significance and Impact

The emergence of periodical cicadas has a profound impact on the ecosystem. While the sheer number of cicadas can seem overwhelming, they play several important roles:

Soil Aeration: As nymphs burrow underground, they create tunnels that help to aerate the soil and improve drainage.
Nutrient Cycling: When cicadas die, their bodies decompose, releasing nutrients back into the soil. This can benefit plant growth and contribute to the overall health of the ecosystem.
Food Source: Cicadas provide a temporary but abundant food source for a variety of animals, including birds, mammals, reptiles, and even other insects. The emergence can lead to a temporary boom in predator populations.
Tree Pruning: Female cicadas lay their eggs in tree branches, which can sometimes cause the branches to die back. This natural pruning can actually benefit trees in the long run by promoting new growth.

Impact on Humans:

While cicadas are ecologically beneficial, their emergence can also have some negative impacts on humans:

Noise Pollution: The loud buzzing of male cicadas can be disruptive, especially in densely populated areas.
Damage to Young Trees: The egg-laying behavior of female cicadas can damage young trees, particularly newly planted ones. It’s recommended to protect young trees with netting during cicada emergences.
Psychological Impact: Some people find the sight and sound of cicadas to be unsettling, leading to anxiety or fear.

Looking Ahead: Predicting Future Emergence

Understanding the 2021 cicada map in Tennessee is crucial for predicting future emergences. By analyzing the data collected from citizen science projects, academic research, and historical records, scientists can develop models to forecast when and where cicadas are likely to emerge in the coming years. This information can be valuable for homeowners, farmers, and land managers who want to prepare for the next cicada spectacle.

While Brood X has retreated underground, the memory of their 2021 visit remains. The knowledge gained from mapping their emergence in Tennessee will continue to inform our understanding of these fascinating insects and their role in the ecosystem. The cicada’s song may be silent for now, but it will undoubtedly return, reminding us of the cyclical nature of life and the enduring power of the natural world.

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