Cicadas are among the most ecologically productive insects on Earth, functioning as massive nutrient recyclers, prey for dozens of species, soil engineers, and even indirect regulators of forest health. Their periodic mass emergences, when billions of individuals surface within days, create resource pulses that ripple through food webs from treetops to stream beds. Far from being just a noisy nuisance, cicadas occupy a surprisingly central role in the ecosystems they inhabit, and scientists are still uncovering new ways their influence extends beyond what anyone expected.
Fertilizing the Forest From Below
When periodical cicadas emerge after 13 or 17 years underground, they bring enormous quantities of nutrients with them. Their bodies are rich in nitrogen, and once the adults die and decompose, that nitrogen floods back into the soil. One study tracking a 2015 emergence in a tallgrass prairie landscape measured a below-to-aboveground flux of roughly 1.12 metric tons of nitrogen across the emergence area, corresponding to about 7 kilograms of nitrogen per hectare in and near forested patches.1Ecosphere. Periodical cicada emergence resource pulse tracks forest expansion in a tallgrass prairie landscape That is a substantial natural fertilizer event, delivered free of charge.
The effects of all that decomposing biomass show up quickly in the soil. Research on periodical cicada carcasses found that they boosted plant-available nutrients and stimulated activity among soil microbial-feeding invertebrates. Decomposing cicadas propagated nutrient pulses belowground, driving increased nutrient mineralization in the soil.2PubMed Central. Acute resource pulses from periodical cicadas propagate to belowground food webs but do not affect tree performance The same study found, however, that these soil-level benefits did not translate into measurable changes in tree growth, a reminder that nutrient cycling and tree performance operate on different timescales.
Smaller plants seem to respond more directly. Experiments with American bellflower rosettes showed that adding cicada carcasses to the soil increased mean plant biomass by about 61 percent compared to plants without the supplement, and supplemented plants had roughly 20 percent higher nitrogen concentrations in their foliage.3Arthropod-Plant Interactions. Resource pulses of dead periodical cicadas increase the growth of American bellflower rosettes under competitive and non-competitive conditions Understory plants and herbaceous species, with shallower root systems, seem better positioned to capitalize on these brief nutrient windfalls than deep-rooted trees.
Billions of Tiny Soil Engineers
Cicada nymphs spend years underground, and when they finally dig their way out, they leave behind networks of finger-width tunnels. These burrows are not trivial. A study of the 2021 Brood X emergence measured an 80.8 percent increase in the rate at which water could infiltrate the soil in undisturbed forest sites with cicada burrows compared to nearby soil without them. The burrows essentially act as conduits that funnel rainwater deeper into the soil profile, potentially recharging shallow groundwater and reducing surface runoff.4Hydrological Processes. Influence of the 2021 Brood X cicada emergence on near surface hydrology in forested and urban landscapes
The benefit was concentrated in natural landscapes. In urbanized areas, where soils tend to be compacted by foot traffic, construction, and landscaping, the burrows did not improve infiltration in the same way. Compacted urban soils essentially collapsed around the tunnels, neutralizing the macropore effect that made forest soils so much more permeable. This distinction matters for stormwater management: in forests and parks with relatively intact soil, a cicada emergence year may quietly reduce local flooding and improve groundwater recharge for a period after the insects are gone.
A Buffet for Birds and Mammals
Perhaps the most visible ecological role cicadas play is as food. When billions of protein-rich insects blanket the landscape, animals notice. A study of red-winged blackbirds during a periodical cicada emergence found that the birds shifted their foraging into adjacent forests to exploit the sudden abundance. During the cicada period, nestling biomass increased, nestling survival improved because fewer chicks starved, and fledging success went up.5PubMed. Effects of superabundant food on breeding success and behavior of the red-winged blackbird The food pulse essentially removed the normal limits on how many offspring the population could successfully raise that season.
It is not just small birds. Research on coyotes during a 13-year cicada emergence found that cicadas became the single most frequently occurring food item in coyote diets during the emergence year, overtaking the small mammals and rabbits that normally dominate. Dietary diversity dropped significantly, with the Shannon diversity index falling from a range of 1.46–1.52 in non-emergence years to 1.24 during the emergence, because the coyotes were so heavily focused on cicadas.6PubMed Central. Response of an Apex Mammalian Predator to an Emergence of 13-Year Periodical Cicadas When a top predator reorganizes its entire diet around a single insect, you get a sense of just how much biomass these emergences represent.
The Surprising Cascade That Doubles Caterpillar Damage
One of the more counterintuitive findings about cicada emergences is that they can temporarily harm trees, not by what cicadas do, but by what birds stop doing. During the 2021 Brood X emergence, researchers documented that more than 80 bird species switched their foraging to include cicadas. With so many birds gorging on cicadas instead of hunting caterpillars, herbivorous insects were effectively released from predation. The result: both caterpillar densities and accumulated leaf damage on oak trees roughly doubled.7PubMed. Periodical cicadas disrupt trophic dynamics through community-level shifts in avian foraging
This is a textbook trophic cascade, where a disruption at one level of the food web reverberates up or down the chain. The cicadas themselves are not eating the oak leaves. They are simply so irresistible as a food source that birds temporarily abandon their usual insect prey, and those prey populations explode. Oak trees can typically tolerate a bad year of caterpillar damage and recover, but the finding illustrates how deeply a cicada emergence reshapes ecological interactions beyond the obvious.
Dendrochronological research adds another layer. A study of five tree species in Indiana found no evidence that cicada nymphs feeding on tree roots during their underground years detectably harmed tree growth. But three of the five species showed a significant dip in ring width the year of or the year after an emergence, followed by an increase about five years later.8BioOne Complete. The Effect of Periodical Cicadas on Growth of Five Tree Species in Midwestern Deciduous Forests The initial dip could reflect the combined stress of egg-laying damage to branches and the caterpillar surge, while the later rebound may reflect the delayed nutrient boost from decomposing cicada bodies finally reaching tree roots.
Feeding Streams and Ponds
Cicadas do not just feed the land. Some of the emergent biomass inevitably falls into woodland streams, ponds, and other small water bodies, creating a pulse of high-quality organic matter. Experiments simulating cicada deposition in pond-like mesocosms found that the carcasses rapidly affected aquatic food webs, leading to substantial increases in both dissolved nutrients and the biomass of aquatic organisms. The size of the effect scaled with how many cicada carcasses entered the water.9PubMed Central. Allochthonous subsidy of periodical cicadas affects the dynamics and stability of pond communities For small forest ponds that are often nutrient-poor, a cicada emergence year can be a significant event, boosting algae growth, zooplankton, and the small fish or amphibians that depend on them.
Reshaping the Soundscape
Cicada choruses are famously loud, and that noise is not just an annoyance for humans. It actively shapes how other animals communicate. Research in a neotropical wet forest found that birds significantly altered the timing and frequency of their songs in response to cicada calls. Birds avoided overlapping with cicada signals by reducing or shutting down vocalizations when cicadas were buzzing in the same frequency range. When birds did sing at the same time, they shifted to frequencies that did not overlap with the cicada calls.10PubMed Central. Cicadas impact bird communication in a noisy tropical rainforest
Playback experiments confirmed this was a direct response: broadcasting recorded cicada buzzes during the dawn chorus suppressed calling activity in bird species whose songs fell within the cicada’s frequency bandwidth.11Animal Behaviour. Insect noise avoidance in the dawn chorus of Neotropical birds In urban areas, the effect gets layered on top of human-generated noise. A study of urban and rural bird songs found that when cicadas were present, birds sang at lower maximum and peak frequencies and used a narrower bandwidth. The reduction in maximum frequency was particularly pronounced in urban settings, where birds were already contending with traffic and construction noise.12Behavioral Ecology. Multiple constraints on urban bird communication: both abiotic and biotic noise shape songs in cities
Cicadas are, in effect, an acoustic force that other species must work around. This has real consequences for bird mating and territory defense, since songs that get drowned out or compressed into a narrow frequency band may be less effective at attracting mates or warning rivals. Cicada noise is a selective pressure that shapes avian behavior season after season.
The Fungus That Hijacks Their Behavior
Cicadas support their own specialized parasites, and the strangest may be Massospora cicadina, a fungus that infects periodical cicadas during their adult emergence. The fungus colonizes the cicada’s abdomen, eventually replacing it with a chalky mass of spores, yet infected cicadas keep moving and attempting to mate. The truly bizarre part is the behavioral manipulation: infected males begin mimicking the wing-flick signals that females use to attract mates. Uninfected males, fooled by the signal, approach and attempt to copulate, spreading spores in the process. The fungus essentially converts its host into a spore-dispersal machine by hijacking sexual communication.13PubMed Central. A specialized fungal parasite (Massospora cicadina) hijacks the sexual signals of periodical cicadas (Hemiptera: Cicadidae: Magicicada)
The fungus operates in two stages. Early-stage infections produce spores that spread among living adult cicadas, partly through the sexual-deception mechanism. Late-stage infections produce a different type of spore that disperses to the soil, lying dormant to infect the next generation of nymphs when they eventually emerge years later.14PubMed. Histologic findings of Massospora cicadina infection in periodical cicadas (Magicicada septendecim) Massospora is not “good for” cicadas, obviously, but it is part of the ecological web they sustain. Specialized parasites like this one depend entirely on cicada populations for their own survival and represent a unique branch of fungal biology that would not exist without their hosts.
Why Prime Numbers Matter
The 13- and 17-year life cycles of periodical cicadas have puzzled biologists for generations. Both are prime numbers, and that appears to be more than a coincidence. A mathematical predator-prey model demonstrated that prime-numbered life cycles naturally emerge as an evolutionary stable strategy because they minimize overlap with potential predators or parasites that might synchronize to shorter, non-prime cycles. If a predator had a two-year boom-bust cycle, for instance, it would align with a cicada emerging every 12 or 14 years far more often than one emerging every 13.15Complexity. Prime number selection of cycles in a predator‐prey model
The sheer size of periodical cicada emergences also works as a survival strategy. By flooding the landscape with more individuals than any predator population could consume, the “leftover” cicadas survive to reproduce. Stragglers that emerge off-cycle, whether a year early or a year late, tend not to fare well because they face the full force of local predators without safety in numbers.16PubMed Central. Predation-driven geographical isolation of broods in periodical cicadas The combination of prime-numbered cycles and mass synchrony creates a defense that no individual cicada could achieve on its own.
Cicadas in Cities
Urbanization is not kind to cicadas. A study in Japan found that soil compaction from development reduces cicada diversity, because compacted ground makes it harder for nymphs to burrow down to tree roots after hatching and harder for mature nymphs to tunnel back up to the surface years later.17PubMed Central. Urban soil compaction reduces cicada diversity Cities tend to support fewer cicada species than surrounding natural areas, and the species that persist are often the ones most tolerant of disturbed soils.
Rainfall timing also shapes how cicada emergences play out in urban habitats. Research on annual cicadas found that emergence synchrony differed between urban and forested sites, with forested parks showing broader, less synchronized emergence windows.18PubMed Central. Rainfall Timing as a Key Driver of Cicada Peak Emergence in Urban Habitats Climate change adds another wrinkle: since soil temperature acts as a trigger for emergence, anomalous warming could push cicadas out of sync with the photoperiod cues they also rely on, potentially altering the timing and intensity of emergence pulses in unpredictable ways.
Inspiring Germ-Killing Surfaces
Cicada wings have attracted serious attention from materials scientists because of something invisible to the naked eye: their surfaces are covered in tiny nanopillars arranged in a hexagonal pattern. These pillars physically rupture bacteria that land on them, killing the microbes without any chemical agent involved. The mechanism is purely mechanical: a bacterial cell settles onto the surface, gets stretched between the pillars, and tears apart.19PubMed Central. Mechano-bactericidal activity of cicada wing nanostructures against gram-positive bacteria
Not all cicada species are equally lethal to bacteria. Testing across several species revealed that wing surface coverage by bacteria was similar (around 20–25 percent), but species with taller, more densely packed nanopillars killed significantly more of the microbes that did land. The correlation between nanostructure scale and bactericidal effectiveness has been robust across multiple studies.20PubMed. Cicada Wing Surface Topography: An Investigation into the Bactericidal Properties of Nanostructural Features The nanopillars are also super-hydrophobic and self-cleaning, meaning water beads up and rolls off, carrying debris with it.21Applied Nanoscience. Verifying antibacterial properties of nanopillars on cicada wings
Engineers are already working to replicate these nanostructures on medical implants, hospital surfaces, and food-processing equipment. The appeal is that a surface modeled on a cicada wing could kill bacteria indefinitely without leaching chemicals, without promoting antibiotic resistance, and without needing to be reapplied. It is a case where a feature that evolved to keep a bug’s wings clean could end up saving human lives in operating rooms.
Cicadas as Food for Humans
Eating insects, including cicadas, is nothing new. Edible insects have been part of human diets for thousands of years, and cicadas fall within the order Hemiptera, one of the eight major insect orders consumed around the world.22PubMed Central. Edible insects, a valuable protein source from ancient to modern times Recent nutritional analysis of cicada species has found them to be high in protein and other nutrients across different developmental stages, with researchers concluding they hold real potential as a sustainable food source for the broader food industry.23Food Chemistry: X. Chemical composition and nutritional profile of cicada (Meimuna opalifera Walker) at different developmental stages: Implications for functional food applications
In the United States, periodical cicada emergences have prompted a wave of culinary curiosity each time a major brood surfaces. The freshly molted nymphs, called tenerals, are considered the most palatable stage because their exoskeletons have not yet hardened. They are often described as having a mild, nutty flavor. People with shellfish allergies are typically cautioned to avoid cicadas, since insects and crustaceans share enough biochemistry that cross-reactions are possible. Beyond novelty, the broader argument for eating cicadas mirrors the case for insect protein in general: they convert feed into body mass efficiently, require minimal land and water, and produce far less greenhouse gas per gram of protein than conventional livestock.
What Cicada Decomposition Does to the Atmosphere
The mass die-off that follows every emergence also has microbial consequences. Researchers studying the necrobiome, the community of microorganisms that colonize and break down dead cicadas, found that the microbial communities on decomposing cicada bodies were significantly different from those in the surrounding soil.24Applied Soil Ecology. Cicada necrobiome mediates greenhouse and trace gas pulses following periodic mass emergence This matters because the particular microbes involved in decomposition determine which gases are released. When billions of cicada carcasses decay simultaneously, the microbial activity produces measurable pulses of greenhouse and trace gases. The scale of these pulses depends on how many cicadas die in a given area and how quickly decomposition proceeds, but it adds a rarely discussed dimension to cicada ecology: even in death, they are altering the local chemical environment in ways that ripple through soil and atmosphere alike.