The mass emergence of cicadas is often followed by a dramatic scene of mass death. These insects spend years developing beneath the soil, appearing above ground for a brief, noisy period before their bodies litter the landscape. The end of the adult life stage results from several distinct factors, including programmed biological failure, external environmental pressures, and a bizarre, mind-controlling fungal pathogen. Understanding the cicada’s death requires examining its biological purpose and the threats it faces during its short time above ground.
Death by Design: The End of the Adult Life Cycle
The fundamental cause of death for an adult cicada is a natural biological endpoint driven entirely by reproduction. Once emerged, the adult form is engineered for a singular mission: to mate and lay eggs. This accelerated adult stage lasts approximately four to six weeks.
This intense reproductive period is physically exhausting and quickly leads to senescence. Males expend massive energy on loud calling songs produced using specialized organs called tymbals to attract mates. Females invest significant energy using a sharp ovipositor to slice slits into woody plant stems where they deposit hundreds of eggs.
Adult cicadas feed by sucking xylem fluids from plants, but this energy intake is insufficient to sustain them beyond the reproductive cycle. Their bodily systems wear out under the strain of continuous activity. Once reproduction is complete, the insect’s biological clock runs out, leading to natural death shortly thereafter.
External Threats: Predation and Accidents
While natural senescence is the ultimate fate for most, many adult cicadas die due to external pressures. The mass emergence strategy is a defense mechanism known as predator satiation. The sheer number of insects overwhelms local predators, ensuring enough individuals survive to reproduce. Many cicadas are consumed by a wide range of animals, including birds, raccoons, squirrels, fish, and domestic pets, who gorge themselves on the sudden protein-rich feast.
Many cicadas also succumb to simple accidents and environmental factors. Extreme weather, such as sudden thunderstorms, can kill large numbers of the insects. Human infrastructure poses significant risks, with individuals dying from being struck by vehicles or killed by lawnmowers.
The widespread use of pesticides to control the insects is an ineffective and harmful threat. Spraying chemicals is largely futile because so many cicadas emerge at once. Pesticides also pose a greater danger to beneficial insects and the animals that rely on cicadas as a food source.
Fungal Infection: The Zombie Cicada Phenomenon
One unusual cause of death is the fungus Massospora cicadina, which transforms its host into a spore-distributing “zombie.” This fungus targets adult cicadas, often infecting them before they succumb to natural causes. The infection begins as the fungus consumes the cicada’s internal abdominal tissue, replacing the rear segments with a dense, chalky plug of fungal spores.
The infected insect does not die immediately; instead, it continues to fly and interact with healthy individuals, actively spreading the pathogen. The fungus employs behavioral manipulation, inducing a hypersexual state that drives the infected cicadas to seek out mates with increased urgency.
The fungus manipulates infected male cicadas to mimic the wing-flicking behavior used by females as a mating signal. This false invitation attracts healthy males who attempt to copulate, turning the fungus into a sexually transmitted disease. Psychoactive compounds within the fungal plug, including psilocybin and cathinone, are believed to cause the cicadas’ hyperactive behavior.
The fungus essentially hijacks the host’s body, compelling it to maximize the spread of spores. This active host transmission often leads to the infection of a significant portion of the population during an emergence, ensuring the fungus’s survival until the next cycle.
Short Lives vs. Long Lives: Comparing Annual and Periodical Cicada Lifespans
The brief adult life stage is often mistaken for the insect’s entire lifespan, but it is only the final chapter of a much longer developmental period. Cicadas are categorized into two groups: annual and periodical. The difference in their lifespan refers to the duration of their time spent underground as nymphs, not the adult phase.
Annual cicadas appear every year and have life cycles ranging from two to five years, with the majority of that time spent below the soil. Periodical cicadas, found exclusively in North America, emerge only every 13 or 17 years. These insects spend 99.5% of their lives as subterranean nymphs, feeding on xylem from tree roots.
In both types, the adult life stage is consistently short, lasting only a few weeks once they emerge. The death observed after the emergence is simply the biological end of the adult form, which has successfully completed its role in the continuation of the species.