Cicadoidea is the superfamily that contains every cicada on Earth, from the deafening choruses of periodical species in North American forests to two reclusive, silent species clinging to tree trunks in the mountains of Tasmania. The group sits within the order Hemiptera, the true bugs, and splits into two living families whose evolutionary paths diverged roughly in the Middle Jurassic. That split, between the familiar loud cicadas and a pair of nearly unknown Australian relicts, frames much of what makes Cicadoidea such a rich subject for biology: sound production, extreme life cycles, symbiotic bacteria, ecological engineering, and wing surfaces that kill bacteria on contact.
Two Living Families, Worlds Apart
The vast majority of the roughly 3,000 described cicada species belong to Cicadidae, the family most people picture when they hear the word “cicada.” These are the insects whose males produce some of the loudest sounds in the insect world, calling from trees across every continent except Antarctica. The second family, Tettigarctidae, consists of just two living species in the genus Tettigarcta, both restricted to cool, forested highlands of southeastern Australia. Tettigarctids do not sing in any way a human ear can detect. Instead, they communicate through low-intensity vibrations transmitted through the plant substrate they sit on, a habit researchers consider an ancestral trait retained from before loud airborne calling evolved.1Journal of Natural History. Substrate-transmitted acoustic signals of the primitive cicada, Tettigarcta crinita Distant (Hemiptera Cicadoidea, Tettigarctidae) The contrast between the two families is striking: Cicadidae blankets the tropics and temperate zones with thousands of species and an enormous acoustic footprint, while Tettigarctidae barely persists as a living fossil in a handful of mountain refuges.
Mesozoic Roots and a Jurassic Split
Fossils and phylogenetic analyses push the origin of Cicadoidea deep into the Mesozoic. A 2024 study analyzing both new Mesozoic fossils and existing specimens concluded that the two living families, Cicadidae and Tettigarctidae, may have diverged at or by the Middle Jurassic, roughly 170 million years ago.2Nature Communications. Mesozoic evolution of cicadas and their origins of vocalization and root feeding That work also reshuffled some long-held taxonomic assumptions. Several Mesozoic fossils previously classified as Tettigarctidae turned out to be phylogenetically closer to modern Cicadidae, meaning the apparent diversity of ancient “hairy cicadas” was partly an artifact of superficial resemblance.
Fossil nymphs from mid-Cretaceous deposits reveal that cicadas had already adopted a subterranean lifestyle by that point. These nymphs had fossorial forelegs built for digging and piercing-sucking mouthparts suited for tapping into plant roots underground.2Nature Communications. Mesozoic evolution of cicadas and their origins of vocalization and root feeding The same study found tymbal-like structures in mid-Cretaceous adult fossils, though anatomical analysis suggests those ancient cicadas were either silent, like modern Tettigarctidae, or capable of only faint tymbal-related sounds. The full-throated calls that define modern Cicadidae apparently evolved later, possibly in tandem with the radiation of flowering trees whose canopies offered good calling perches and whose roots fed the nymphs below.
How Cicadas Make the Loudest Insect Sounds on Earth
Male cicadas in Cicadidae call using a pair of specialized muscles that rank among the fastest in the animal kingdom. These tymbal muscles sit in the anterior abdominal cavity and contract at around 50 times per second, pulling on stiff, ribbed cuticular membranes called tymbals located beneath the folded wings. Each contraction causes five to six sequential stages of rib buckling in the tymbal. When the muscle relaxes slightly, resilin, a rubber-like protein embedded in the ribs, snaps the structure back, generating another burst of sound. The result is a rapid-fire series of clicks that fuse into a continuous tone or pulse train.3PubMed. What the buzz was all about: superfast song muscles rattle the tymbals of male periodical cicadas
A 2025 study took this understanding further by modeling the tymbal as a biological metastructure, a system of periodically arranged ribs that acts as a mechanical frequency filter. The researchers built a model using chains of bistable oscillators coupled to resonators, successfully capturing both the snap-through dynamics of the tymbals and the acoustic filtering that shapes the final call.4PubMed Central. The tymbal of a cicada: nature’s sound-generating metastructure This framework helps explain why different species, all using the same basic organ, can produce calls with wildly different frequencies, rhythms, and timbres. The rib spacing, thickness, and curvature vary among species, effectively tuning the metastructure to generate each species’ distinctive song.
Life Underground on a Starvation Diet
Most of a cicada’s life is spent underground as a nymph, and it is not a comfortable existence. Nymphs tap into tree roots and feed on xylem fluid, the watery sap that moves minerals upward through a plant’s vascular system. Xylem is extremely dilute compared to phloem, the sugar-rich sap that aphids and other plant-feeding insects prefer. Histological studies of tree roots where periodical cicada nymphs had fed confirmed that every salivary sheath ended in xylem vessels, with none found in phloem cells.5Ecological Entomology. Xylem feeding by periodical cicada nymphs on tree roots This nutritional poverty likely explains why nymphal development takes so many years. Periodical cicadas in North America spend either 13 or 17 years underground, and even annual species with shorter cycles still take multiple years to mature.
To survive on such a poor food source, cicadas depend on bacterial partners. Two ancient endosymbiotic bacteria, informally named Sulcia and Hodgkinia, live within specialized cells in the cicada’s body and are passed from mother to offspring through the eggs. These bacteria synthesize the essential amino acids and vitamins that xylem sap cannot supply.6mBio. Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas The relationship is obligate on both sides: the bacteria cannot live outside the insect, and the insect cannot develop without them. In some cicada lineages, Hodgkinia’s genome has fragmented into multiple co-dependent strains, each retaining a different subset of essential genes, a degree of symbiotic complexity almost unheard of elsewhere in the insect world.7Genome Biology and Evolution. No Transcriptional Compensation for Extreme Gene Dosage Imbalance in Fragmented Bacterial Endosymbionts of Cicadas
Why 13 and 17 Years
The prime-numbered life cycles of North American periodical cicadas (genus Magicicada) have puzzled biologists for over a century. One leading explanation is the hybridization hypothesis: if cicadas with different cycle lengths occasionally interbreed, the offspring might emerge off-schedule and fail to find mates. Prime-numbered cycles minimize the overlap between broods of different lengths, because primes share few common multiples. A simulation model testing this idea found that non-prime intervals disappeared quickly from the population relative to prime-numbered ones, and that the 13- and 17-year phenotypes could evolve and coexist under realistic assumptions about survival and reproduction.8Evolution. SELECTION FOR PRIME-NUMBER INTERVALS IN A NUMERICAL MODEL OF PERIODICAL CICADA EVOLUTION
The two cycle lengths also differ in biology beyond just timing. Research on genetic differences between 13-year and 17-year cicadas shows that 13-year nymphs grow faster than their 17-year counterparts.9Ecological Research. Life‐cycle control of 13‐ and 17‐year periodical cicadas: A hypothesis and its implication in the evolutionary process Meanwhile, 17-year adults emerge with heavier ovaries, meaning greater egg-producing capacity. For at least one species, Magicicada cassini, 17-year females had ovaries about 1.8 times heavier than their 13-year relatives, and this extra fecundity could outweigh the advantage of more frequent reproduction that comes with a shorter cycle.10PubMed. Evolution of prolonged development: a life table analysis for periodical cicadas Mitochondrial genomic studies confirm that the major species groups within Magicicada each contain clearly defined phylogeographic subdivisions, an eastern, a middle, and a western lineage, suggesting that geographic isolation during glacial periods shaped the diversification of both 13-year and 17-year forms.11Molecular Biology and Evolution. Mitochondrial Genomics Reveals Shared Phylogeographic Patterns and Demographic History among Three Periodical Cicada Species Groups
What Happens When Billions of Cicadas Die at Once
Periodical cicada emergences are among the largest insect events on the planet, with population densities that can reach hundreds of thousands of individuals per acre. After a few weeks of mating and egg-laying, the adults die and their bodies blanket the forest floor. This mass die-off creates a nutrient pulse that reverberates through the ecosystem. Decomposing cicada carcasses directly increase microbial biomass and nitrogen availability in forest soils, with indirect effects on plant growth and reproduction, essentially creating a “bottom-up cascade” linking above-ground and below-ground components of the forest.12PubMed. Periodical cicadas as resource pulses in North American forests
One experimental study added cicada bodies to soil around sycamore trees and tracked the effects over four years. The decaying cicadas shifted the community composition of soil nematodes, boosting the abundance of bacterial-feeding and fungal-feeding species. Nutrient mineralization increased. But the extra nutrients did not translate into measurable changes in tree growth, suggesting that even a massive nutrient pulse can be absorbed and dampened by the soil food web before reaching the trees.13PubMed Central. Acute resource pulses from periodical cicadas propagate to belowground food webs but do not affect tree performance The decomposition also has atmospheric consequences: decaying carcasses released nitrous oxide and ammonia at rates roughly 35 times the annual average for U.S. forest soils, sustained over about three weeks.14Applied Soil Ecology. Cicada necrobiome mediates greenhouse and trace gas pulses following periodic mass emergence
The effects run through the animal food web too. During the 2021 Brood X emergence, more than 80 bird species opportunistically switched their diets to feed heavily on cicadas. With so many birds gorging on the easy protein, predation pressure on caterpillars dropped sharply, roughly doubling caterpillar densities and the leaf damage they caused on host oak trees.15PubMed. Periodical cicadas disrupt trophic dynamics through community-level shifts in avian foraging A single insect emergence event, in other words, rewired the forest’s food web for weeks.
Egg-Laying Damage to Trees
Female cicadas lay eggs by slicing into twigs and small branches with a saw-like ovipositor, depositing eggs in rows inside the wood. For mature trees in forests, this flagging of branch tips is mostly cosmetic. But ornamental and newly planted trees can suffer real harm. A study examining oviposition damage across 69 tree and shrub species found that nearly a third experienced wilting and branch death in the same season. In the two years following emergence, healing ranged from none at all, with progressive dieback, to rapid and complete recovery, depending on the plant species. Heartwood decay and discoloration sometimes progressed from the wounded branches into the main stem.16Environmental Entomology. Damage to Ornamental Trees and Shrubs Resulting from Oviposition by Periodical Cicada Arborists in periodical cicada regions commonly advise delaying the planting of young fruit trees and ornamental species until the year after an emergence.
A Fungus That Makes Zombies
Among the strangest chapters in cicada biology is the relationship with Massospora, a genus of fungal pathogens that specializes in cicadas. Massospora cicadina infects periodical cicadas, replacing the insect’s abdomen with a chalky mass of fungal spores while the cicada remains alive and active. Infected males continue to call and attempt to mate, and some even mimic female wing-flick signals to attract other males, spreading spores with each encounter.17Scientific Reports. A specialized fungal parasite (Massospora cicadina) hijacks the sexual signals of periodical cicadas (Hemiptera: Cicadidae: Magicicada)
The mechanism behind this behavioral hijacking may be chemical. Metabolomic analysis of infected cicadas found cathinone, an amphetamine-like compound normally associated with the khat plant, in M. cicadina-infected periodical cicadas. In annual cicadas infected with related Massospora species, researchers instead found psilocybin, the psychoactive compound in “magic mushrooms.” The fungal genomes lacked recognizable versions of the enzymes known to produce these compounds in plants and mushrooms, suggesting that Massospora may synthesize them through entirely novel biochemical pathways.18Fungal Ecology. Psychoactive plant- and mushroom-associated alkaloids from two behavior modifying cicada pathogens The discovery raised eyebrows well beyond entomology. A fungus drugging its insect host with psychoactive compounds to keep it mobile and socially engaged while its body disintegrates is about as close to real-world zombie fiction as biology gets.
Parasitoid Flies That Listen In
Cicada calls are not only heard by prospective mates. Several species of sarcophagid flies in the genus Emblemasoma are acoustic parasitoids that eavesdrop on cicada songs to find hosts for their larvae. Female E. erro use the calling song of Tibicen dorsatus as a long-range homing beacon, then rely on visual cues, specifically the host’s physical movement, to complete the final attack and deposit larvae directly onto the cicada.19PubMed Central. Infection behavior, life history, and host parasitism rates of Emblemasoma erro (Diptera: Sarcophagidae), an acoustically hunting parasitoid of the cicada Tibicen dorsatus (Hemiptera: Cicadidae) Even male flies and non-gravid females perform phonotaxis toward cicada sounds, apparently using the calls to locate aggregations where they can find mates of their own species.20PubMed Central. Eavesdropping to Find Mates: The Function of Male Hearing for a Cicada-Hunting Parasitoid Fly, Emblemasoma erro (Diptera: Sarcophagidae) For cicadas, then, calling is a calculated risk: too quiet and no female hears you; too conspicuous and a fly deposits larvae on your back.
Biogeography Across Oceans
Cicadas occupy an unusually wide range of habitats for a group whose nymphs are obligately subterranean. One of the most species-rich cicada tribes, Cicadettini, turns out to have originated in Australasia and subsequently spread worldwide. Within Australia, Cicadettini is more widely distributed than any other cicada tribe, thriving in temperate, arid, and monsoonal habitats while being nearly absent from rainforests.21Systematic Biology. Inflation of Molecular Clock Rates and Dates: Molecular Phylogenetics, Biogeography, and Diversification of a Global Cicada Radiation from Australasia (Hemiptera: Cicadidae: Cicadettini) A separate study of another Australian cicada complex, Pauropsalta, found that multiple lineages invaded arid habitats independently rather than explosively radiating from a single colonization event. Relictual groups persist in isolated mesic “habitat islands” on ancient pre-Mesozoic terrain.22Systematic Biology. How the Aridification of Australia Structured the Biogeography and Influenced the Diversification of a Large Lineage of Australian Cicadas
New Zealand’s cicadas tell a different dispersal story. The islands’ cicada fauna forms two distinct lineages: one clusters with Australian taxa, the other with New Caledonian taxa. Molecular clock estimates place both invasions within the last 12 million years, well after New Zealand became geographically isolated. Cicadas must have crossed substantial ocean gaps to reach the islands, probably carried by storm winds.23Journal of Biogeography. Biogeography and phylogeny of the New Zealand cicada genera (Hemiptera: Cicadidae) based on nuclear and mitochondrial DNA data
Wing Nanostructures That Kill Bacteria
Cicada wings are covered in dense arrays of nanometer-scale pillars, and these pillars do something unexpected: they physically destroy bacteria. When Pseudomonas aeruginosa cells land on a cicada wing, they are not repelled by the hydrophobic surface. Instead, the cells settle between the pillars, their membranes stretch and deform around the sharp structures, and they rupture.24PubMed. Natural bactericidal surfaces: mechanical rupture of Pseudomonas aeruginosa cells by cicada wings The killing mechanism is entirely physical: an “adhere-deform-rupture” process that works regardless of the wing’s chemical composition.25PubMed Central. Mechano-bactericidal activity of cicada wing nanostructures against gram-positive bacteria The nanopillar arrays are hexagonally arranged, super-hydrophobic, and self-cleaning, with pillar heights that vary by species.26Applied Nanoscience. Verifying antibacterial properties of nanopillars on cicada wings
Materials scientists have taken notice. The discovery that a naturally occurring surface can kill bacteria mechanically, without any antibiotic chemicals, has inspired efforts to create synthetic nanostructured surfaces for medical implants, hospital surfaces, and food-processing equipment. Early cicada wing studies focused on gram-negative bacteria, but more recent work confirms the mechanism also works against gram-positive species, broadening the potential applications. The challenge remains scaling production: replicating the precise geometry of cicada nanopillars at industrial volumes is not yet economically practical, but the biological proof of concept has opened a new direction in antimicrobial design.
Cicadas as Food
Cicadas have been eaten by humans across Asia, Africa, and the Americas for millennia, and nutritional analyses are beginning to show why they remain culturally valued. A detailed chemical study of Meimuna opalifera at different developmental stages found that nymphs are especially rich in tocopherols (a form of vitamin E) at about 13.7 milligrams per gram total, and that essential amino acid content increases with maturity, with methionine predominating across all stages. Nymphs also contained substantial eicosapentaenoic acid (EPA), an omega-3 fatty acid, at concentrations around 880 milligrams per 100 grams, higher than in adult cicadas.27PubMed Central. Chemical composition and nutritional profile of cicada (Meimuna opalifera Walker) at different developmental stages: Implications for functional food applications As edible insect research expands, cicadas are increasingly discussed as candidates for functional food ingredients, though cultural acceptance remains the larger barrier in many Western markets.
Warming Temperatures and Earlier Emergence
Climate change is beginning to alter cicada phenology in measurable ways. A study of the Japanese cicada Graptopsaltria nigrofuscata found that higher temperatures from midsummer to early winter in the previous year are pushing emergence dates earlier. The proposed mechanism is straightforward: warmer soil temperatures accelerate nymphal growth rates, allowing nymphs to reach their final molt sooner.28Ecological Entomology. Exploring the factors influencing the first singing date of a cicada, Graptopsaltria nigrofuscata: How will it be affected by climate change? For annual cicadas, whose emergence timing depends partly on soil temperature thresholds, the shift might simply mean hearing choruses a week or two earlier in the season. For periodical cicadas, with their rigid multi-year clocks, the consequences could be more disruptive. There are already scattered reports of “straggler” periodical cicadas, individuals that emerge a year or four years early, possibly due to accelerated development in warming soils. Whether warming could eventually fracture entire broods or cause cycle-length switches remains an open question.
Cooling Off in the Desert
Not all cicadas live in humid forests. The desert cicada Diceroprocta apache thrives in the extreme heat of the American Southwest and manages a physiological trick unusual among insects: evaporative cooling. By pumping xylem water up from the plant it feeds on and releasing it through cuticular pores on its thorax and abdomen, this species can keep its body temperature as much as 5°C below an ambient temperature of 42°C. The cooling kicks in between 37 and 38°C and comes at a surprisingly low metabolic cost, though its duration depends on the cicada’s hydration state and how fast it can draw water from its host plant.29Journal of Experimental Biology. Evaporative Cooling in the Desert Cicada: Thermal Efficiency and Water/Metabolic Costs Most insects simply stop being active when ambient temperatures climb above 40°C. Diceroprocta apache instead keeps calling and feeding through the hottest hours of the day, occupying a thermal niche that few other insects can tolerate.