The genus Magicicada comprises the periodical cicadas, insects famous for their highly synchronized, multi-year emergences known as broods. These broods spend either 13 or 17 years developing entirely underground before emerging en masse as adults for a brief mating period. This lengthy subterranean existence makes them uniquely vulnerable to human development, as a single construction project can wipe out a generation that has been quietly maturing for over a decade. The long-term nature of their life cycle means that land-use changes, such as urbanization and deforestation, have a disproportionately destructive impact on these populations.
Loss of Essential Above-Ground Habitat
The destruction of mature trees and woody vegetation is the first major blow development delivers to a Magicicada brood. The adult stage is dedicated solely to reproduction, and female cicadas require specific host plants for oviposition (egg-laying). A single female uses a specialized organ called an ovipositor to slice into the tender branches of trees and shrubs, depositing 400 to 600 eggs. When host trees are cleared for new construction, the reproductive cycle for that local population is immediately interrupted.
Habitat loss also eliminates the long-term food source required by the new generation of nymphs. After hatching, the tiny nymphs drop to the ground and immediately burrow into the soil, feeding on the xylem fluid found in tree roots. For the next 13 or 17 years, the nymphs rely on the established, extensive root systems of mature trees for sustenance. Removing these large trees eliminates the necessary underground food network, ensuring that newly hatched nymphs cannot survive their extended development period. Ovipositing females often prefer to lay eggs at forest edges, which are frequently targeted for suburban expansion and new development.
Direct Physical Damage to Subterranean Nymphs
The vast majority of the periodical cicada’s life is spent as a nymph feeding underground, making this stage the most susceptible to physical disruption from construction activities. Subterranean nymphs typically reside within the top two feet of soil (approximately 5 to 61 centimeters), where they attach to tree roots to feed. This relatively shallow depth places them directly in the path of heavy machinery and earth-moving operations.
Soil compaction is a primary cause of mortality for the nymphs, often resulting from the repeated movement of bulldozers, dump trucks, and other heavy equipment on a construction site. This machinery dramatically increases soil density, crushing the delicate rootlets the nymphs feed on and often killing the insects themselves. Highly compacted soil also restricts the nymphs’ ability to move, tunnel, and build the exit chimneys they rely on to reach the surface. Increased soil hardness is strongly correlated with a decrease in cicada survivability in urbanized areas.
Furthermore, grading and excavation for foundations, utilities, and driveways directly remove or displace large volumes of topsoil. Since nymphs are concentrated in the uppermost layers, these activities effectively scoop up and discard entire populations of the brood. The loose soil environment necessary for nymphal development and movement is destroyed by this large-scale manipulation, resulting in the localized extinction of the generation that has spent over a decade maturing.
Barriers to Successful Emergence and Chemical Risks
Even if nymphs survive the initial construction phase, they face obstacles when it is time for their synchronized emergence. The widespread installation of impervious surfaces, such as concrete foundations, driveways, sidewalks, and asphalt roads, creates a solid, impenetrable barrier. A nymph that has successfully developed for 13 or 17 years is physically blocked from reaching the surface by this hard material. Nymphs trapped beneath these barriers ultimately die just before completing their metamorphosis.
The increasing use of chemicals in new residential and commercial landscaping further threatens the surviving subterranean nymphs. Although cicadas are not typically the target of residential pest control, the application of pesticides and herbicides can still impact the brood. These chemicals can leach down through the soil and into the root systems where the nymphs are feeding. The chemicals poison the root xylem fluid or directly kill the nymphs, especially during the vulnerable phase when they move closer to the surface to prepare for emergence.
Fertilizer runoff from lawns and landscaping also alters the soil chemistry, potentially affecting the host tree’s root fluid composition and the microorganisms the nymphs rely on. Consequently, a brood that endures the physical destruction of a construction project may still be eliminated by a final layer of concrete or the introduction of toxic compounds into their environment.