Giant cicadas have existed for at least 150 million years. The term applies to both an extinct family of Mesozoic insects called the Palaeontinidae, whose wing lengths could approach 80 millimeters, and to the largest living cicada species, some of which have wingspans exceeding 20 centimeters and bodies thick enough to cover an adult’s palm. Whether you encountered one clinging to a tree in a Malaysian rainforest or found one preserved in Jurassic limestone, the basic body plan is remarkably consistent, and the biology behind these oversized insects is stranger than their size alone suggests.
Prehistoric Giant Cicadas and the Mesozoic Fossil Record
The Palaeontinidae were a family of large cicada-like insects that thrived during the Jurassic and early Cretaceous periods. Researchers studying their fossils have documented a faunal turnover from early to late Palaeontinidae during the latest Jurassic and earliest Cretaceous, accompanied by a morphological shift and a marked improvement in flight abilities, including increased flight speed and enhanced maneuverability.1PubMed Central. Enhanced flight performance and adaptive evolution of Mesozoic giant cicadas These animals were not just large; the later species appear to have been more aerodynamically refined than their predecessors, likely an adaptation to the changing ecosystems and predation pressures of the mid-Mesozoic.
One persistent assumption is that ancient insects were simply scaled-up versions of modern ones, but body-size data spanning both fossil and extant cicadas tells a more nuanced story. Analysis of measurements across fossil and modern species found that body length does not show a pattern of increase from the Mesozoic to the present. Body lengths ranged from roughly 5 to 65 millimeters, and wing lengths from about 6 to 79 millimeters across the entire dataset, fossil and modern combined.2Nature Communications. Mesozoic evolution of cicadas and their origins of vocalization and root feeding In other words, the giants of the Mesozoic were not dramatically larger than the biggest cicadas alive today. What changed over evolutionary time was not maximum size but the composition and flight performance of the lineages that survived.
The Largest Living Species
Among modern cicadas, the largest belong to genera found primarily in Southeast Asia. The empress cicada, Megapomponia imperatoria, is widely considered the largest living cicada species, with a wingspan that can reach roughly 20 centimeters and a body length around 7 centimeters. Other notably large species are found in Australia, South America, and parts of Africa. Size varies considerably even within a single species, influenced by the quality of root-sap resources available to nymphs during their underground development.
Research into cicada flight systems has shown that mass, wing length, wingspan, wing area, and wing loading all correlate with minimum flight temperature between species, as aerodynamic theory predicts. However, the correlation coefficients are low, suggesting the flight system has only minimal influence on the temperature threshold at which a cicada can fly.3PubMed Central. Flight system morphology and minimum flight temperature in North American cicadas For the largest species, which carry more mass per unit of wing area, warm ambient temperatures are more critical for flight than they are for smaller relatives. This helps explain why the biggest cicadas tend to live in tropical or subtropical climates rather than temperate forests.
How Cicadas Produce the Loudest Insect Sounds
If you have stood near a chorus of large cicadas, you know the sound can be physically uncomfortable. Male cicadas produce their calls by oscillating a pair of specialized muscles in the abdomen that pull on and buckle stiff, ribbed membranes called tymbals.4PubMed. What the buzz was all about: superfast song muscles rattle the tymbals of male periodical cicadas Each inward buckle produces a click; the rapid succession of these clicks, amplified by the largely hollow abdomen acting as a resonating chamber, generates the characteristic buzzing or pulsing call.
Recent research has reframed the tymbal not just as a vibrating membrane but as a naturally occurring metastructure, characterized by periodically arranged ribs and built-in frequency filtering. Scientists have modeled it as a chain of bistable oscillators coupled to a chain of resonators, capturing both the snap-through dynamics of the tymbals and the acoustic filtering that follows.5PubMed Central. The tymbal of a cicada: nature’s sound-generating metastructure In larger species, the bigger abdominal cavity amplifies low-frequency components more effectively, producing a deeper, more resonant call that carries over greater distances. This is why the chorus of a large tropical species has a qualitatively different feel than the shrill buzz of a small temperate one.
Decades Underground on a Diet of Dilute Sap
Most of a cicada’s life is spent underground as a nymph, feeding on tree roots. Depending on the species, this subterranean phase lasts anywhere from two to seventeen years. Histological examination of tree roots fed on by periodical cicada nymphs showed that their feeding sheaths terminated in xylem vessels, with no evidence of phloem feeding, confirming that cicada nymphs feed exclusively on xylem sap throughout their development.6Ecological Entomology. Xylem feeding by periodical cicada nymphs on tree roots Xylem sap is nutritionally poor compared to phloem, consisting mostly of water with trace minerals and very few amino acids. The puzzle of how a large insect can grow for years on such a dilute food source has an elegant answer: bacterial partners living inside the cicada’s body.
Isotopic analysis of amino acids in periodical cicadas revealed that several essential amino acids present in the cicada’s tissues were absent from the xylem sap itself. The carbon-isotopic composition of all amino acids in the cicadas was distinctly different from those measured in the xylem, leading researchers to conclude that these amino acids were synthesized from scratch rather than absorbed directly, most likely produced by endosymbiotic bacteria.7Journal of Insect Physiology. Feeding ecology and evidence for amino acid synthesis in the periodical cicada (Magicicada) In effect, the bacteria convert the sparse raw materials in xylem sap into the building blocks the cicada needs to grow. Without this partnership, a xylem-feeding lifestyle at this body size would be metabolically impossible.
Underground, nymphs actively construct their living space. When fifth-instar nymphs of the species Cicadetta calliope were placed in enclosures with layered colored sand, they burrowed immediately, excavating air-filled, sediment-enclosed cells between 20 and 40 millimeters long and averaging 9 millimeters wide.8GeoScienceWorld (PALAIOS). Traces and burrowing behaviors of the cicada nymph Cicadetta calliope: Neoichnology and paleoecological significance of extant soil-dwelling insects These cells are not random tunnels; nymphs maintain them as permanent feeding chambers, repositioning themselves to access new root material as they grow. Larger species build proportionally larger cells, and in some tropical habitats, nymph burrows are dense enough to visibly loosen the upper soil layers.
Finding the Way Out in the Dark
When cicada nymphs finally emerge, they face an immediate challenge: reaching a vertical surface to molt into their winged adult form. A combination of observational and experimental studies demonstrated that emergent cicada nymphs use skototaxis, or movement toward dark silhouettes, to navigate to trees. Nymphs walked directly toward isolated trees regardless of their initial compass direction or the time of day, traveling only about 15 percent farther than the minimum distance necessary. When researchers temporarily obscured the nymphs’ vision, the blinded individuals wandered randomly and rarely found a tree at all. Indoor trials confirmed that the nymphs orient preferentially toward dark objects.9PubMed Central. Emergent Periodical Cicada Nymphs Use Skototaxis to Navigate to Trees For species that emerge in dense forest, this visual strategy is efficient. For giant tropical species emerging in more open habitats, the longer walk to a suitable tree probably increases predation risk, though dense emergences of synchronized species can overwhelm predators through sheer numbers.
Ecological Footprint of Mass Emergences
When billions of cicadas emerge in a synchronized event, die within weeks, and decompose on the forest floor, the nutrient pulse is enormous. Researchers who added adult cicada carcasses to soil around sycamore trees found that the decomposing bodies propagated nutrient effects belowground, stimulating nutrient mineralization and boosting populations of soil microbial-feeding invertebrates. However, these effects did not transfer upward to measurably affect tree performance over a four-year monitoring period.10PubMed Central. Acute resource pulses from periodical cicadas propagate to belowground food webs but do not affect tree performance The trees, it seems, already have access to enough nutrients that an extra pulse of nitrogen and carbon from rotting cicadas does not visibly change their growth. The real beneficiaries are the microbes and tiny invertebrates in the soil food web.
The decomposition also has atmospheric consequences. Field experiments measuring gas fluxes from soil amended with cicada carcasses found that nitrous oxide emissions from carcass-treated plots averaged roughly 29,000 nanograms of nitrogen per square meter per hour, compared to about 2,500 in control plots, peaking around ten days after carcass addition.11Applied Soil Ecology. Cicada necrobiome mediates greenhouse and trace gas pulses following periodic mass emergence Nitrous oxide is a potent greenhouse gas, and while the total contribution from cicada die-offs is modest in a global context, it represents a concentrated, predictable pulse that briefly transforms local soil chemistry.
Even while alive, cicadas interact with their environment in surprising fluid-dynamic ways. Despite weighing only about two grams, cicadas are capable of jetting fluids through remarkably small orifices, a behavior that defies the expectation that such tiny animals should be limited to dripping rather than squirting. Researchers used this observation to develop a unifying fluid dynamics framework that spans surface-tension-dominated insects all the way to gravity-driven mammals.12PubMed Central. Unifying fluidic excretion across life from cicadas to elephants If you have ever had a feeding cicada squirt a stream of liquid on you from several feet away, you have witnessed a minor biomechanical anomaly that challenged established models of insect excretion.
Massospora and the Zombie Fungus
One of the more disturbing aspects of cicada biology involves a fungal pathogen called Massospora cicadina, which infects periodical cicadas and essentially hijacks their bodies. Histological examination of seven infected cicadas from the 2021 Brood X emergence revealed that fungal masses replaced the entire posterior portion of the abdominal cavity, destroying portions of the body wall, reproductive organs, digestive tract, and fat bodies. No appreciable inflammation was noted at the junction of fungal tissue and host tissue, suggesting the fungus suppresses or evades the cicada’s immune response entirely.13PubMed Central. Histologic findings of Massospora cicadina infection in periodical cicadas (Magicicada septendecim)
Infected cicadas continue to fly and attempt to mate even after losing their abdominal contents, effectively dispersing fungal spores to healthy individuals. The fungus produces psychoactive compounds, including cathinone and psilocybin, which may alter the cicada’s behavior to promote transmission. An infected male will sometimes mimic female wing-flick signals to attract other males, broadening the pool of potential new hosts. For large species with correspondingly large abdominal cavities, the volume of fungal spore mass can be considerable, turning the insect into a highly effective spore dispersal vehicle.
Thermal Niche Separation in Tropical Forests
Giant cicada species tend to occupy specific thermal niches within their habitats, and in tropical forests this stratification is especially well documented. Research along transects through tropical forests in South America found a pronounced diversity of thermal responses among cicada species occupying different vertical strata. Species living in the lower and middle layers of the forest canopy had lower thermal tolerances than those living in the exposed upper canopy, even when comparing species that used the same thermoregulatory strategy. Forest-edge species showed more elevated thermal responses than species restricted to the deep understory.14PLoS ONE. Thermal Adaptation and Diversity in Tropical Ecosystems: Evidence from Cicadas
This vertical partitioning of thermal niches helps explain how so many cicada species coexist in a single forest. Rather than competing directly, species are adapted to the specific temperature regime of their preferred stratum, from the cool, humid understory to the hot, sun-exposed canopy. The largest species tend to be canopy dwellers, where higher body temperatures are both tolerable and advantageous for powering flight muscles and producing loud calls. Their size itself contributes to thermal inertia, allowing them to maintain elevated body temperatures more easily than small species can.
Antibacterial Wing Nanostructures and Biomimicry
Cicada wings have attracted intense interest from materials scientists for a reason that has nothing to do with flight. The wing surface is covered in tiny nanopillars, arranged in a hexagonal pattern, that are naturally superhydrophobic and self-cleaning.15Applied Nanoscience. Verifying antibacterial properties of nanopillars on cicada wings More surprisingly, these nanostructures physically kill bacteria. When a bacterium lands on the wing surface, the nanopillars stretch and rupture its cell membrane through a purely mechanical process, without any chemical antimicrobial agent involved.
Research examining this mechanism in detail described it as an “adhere-deform-rupture” sequence. The nanopillar surface exhibits potent bactericidal activity against both gram-positive and gram-negative bacteria, and this effect is entirely physical rather than chemical.16PubMed Central. Mechano-bactericidal activity of cicada wing nanostructures against gram-positive bacteria The geometry and chemistry of the nanopillars vary between species, and these differences matter. Comparative studies of wing surfaces from different cicada species found that differences in nanopillar geometry and molecular composition influence the degree of hydrophobicity, bacterial fouling resistance, and bactericidal effectiveness.17Advanced Materials Interfaces. Molecular and Topographical Organization: Influence on Cicada Wing Wettability and Bactericidal Properties
For engineers, the appeal is clear: a surface that kills bacteria without chemicals would not drive antibiotic resistance and would remain effective indefinitely, since the killing mechanism is structural rather than biochemical. Researchers have been working to replicate cicada wing nanostructures on synthetic materials for use in medical implants, food-processing equipment, and public-touch surfaces. The wings of larger cicada species, with their greater surface area, have provided particularly useful templates for studying how nanopillar dimensions scale with antibacterial performance. Whether the next generation of self-sterilizing hospital surfaces will owe a debt to an insect most people think of only as a noisy summer nuisance remains to be seen, but the research pipeline is well advanced.