Cicadas are almost always the answer. Those loud, buzzing, pulsing sounds filling the air on a summer day come from male cicadas calling for mates, and some species can produce calls approaching 100 decibels at close range. But cicadas are not the only noisy insects in the canopy. Katydids and tree crickets add their own chorus after dark, each using a completely different mechanism to generate sound, and the combined effect can dominate a landscape’s soundscape for months.
Cicadas and the Tymbal
Cicadas belong to the order Hemiptera and are found on every continent except Antarctica. What makes them remarkable is less the volume of their calls than the mechanism behind it. A cicada does not rub body parts together or bang on anything. Instead, it has a pair of ribbed structures on the sides of its abdomen called tymbals. Specialized muscles rapidly buckle these ribbed membranes inward and outward, and each buckle produces a sharp click. When hundreds of these clicks happen per second, they merge into a continuous buzzing drone. The mostly hollow abdomen acts as a resonating chamber, amplifying the sound and broadcasting it outward.
Researchers recently modeled the cicada’s tymbal as a kind of biological “metastructure,” meaning its periodically arranged ribs and built-in filtering properties work together to shape the sound the insect produces. This framework can explain why different cicada species produce such varied songs despite using the same basic anatomy. The rib spacing, the body cavity volume, and the muscle contraction rate all tune the output differently from one species to the next.1PubMed Central. The tymbal of a cicada: nature’s sound-generating metastructure
Male cicadas do all the singing. Females are silent. The entire point of the racket is mate attraction: a male calls, a receptive female responds with a wing-flick signal the male can detect, and he homes in on her. The process is surprisingly precise. Studies on competing males have recorded two distinct call types. Short, rapid bursts make up the bulk of their output, while longer, drawn-out calls appear during direct male-to-male competition. In laboratory recordings of one species, the short calls lasted about 0.14 seconds each and came in bouts of roughly 25 calls, while the longer competitive calls averaged about 2.4 seconds each.2Journal of Experimental Biology. Temporal structure of two call types produced by competing male cicadas
Katydids and Crickets Use a Completely Different System
If the daytime buzz belongs to cicadas, the nighttime concert usually belongs to katydids and crickets. Both are in the order Orthoptera and produce sound through stridulation, which is essentially wing-on-wing friction. A male katydid or cricket has a row of tiny teeth on a vein of one forewing (the file) and a hardened edge on the other forewing (the scraper). When the wings close, the scraper drags across the file, and each tooth impact sends a tiny vibration into a specialized wing cell that acts like a speaker membrane.3PubMed. Complex wing motion during stridulation in the katydid Nastonotus foreli (Orthoptera: Tettigoniidae: Pseudophyllinae) Sound is usually generated during the closing stroke of the wings, though some species can also produce sound during the opening stroke.4PubMed. Reverse stridulatory wing motion produces highly resonant calls in a neotropical katydid (Orthoptera: Tettigoniidae: Pseudophyllinae)
The result is the chirping, trilling, and rasping sounds people hear on warm evenings. Tree crickets tend to produce a steadier, more melodic pulse, while many katydid species sound more like a sharp, repetitive “katy-did, katy-didn’t” phrase, which is where they get their common name. The wing-stroke rates behind these calls are impressive. The mesothoracic muscles that power singing were once thought to be limited to around 100 cycles per second, though some species exceed that figure.5PubMed Central. Cranking up the heat: Relationships between energetically costly song features and the increase in thorax temperature in male crickets and katydids
This mechanism is ancient. Fossil evidence from a Jurassic-era katydid showed a preserved stridulatory apparatus on its forewings. Analysis of the file-and-scraper dimensions indicated the insect produced pure-tone calls tuned to about 6.4 kilohertz, a frequency well within what modern katydids use today. These insects have been filling trees with song for well over 150 million years.6PubMed Central. Wing stridulation in a Jurassic katydid (Insecta, Orthoptera) produced low-pitched musical calls to attract females
Why They Call at Different Times
If you pay attention to timing, you will notice that cicadas dominate during the day, especially in the hot afternoon hours, while katydids and crickets take over at dusk and through the night. This is not random. With dozens of species sharing the same habitat, sound-producing insects face a real problem: acoustic masking. If everyone calls at the same time and the same frequency, nobody gets heard. The solution is partitioning, dividing up the available acoustic space by time of day and by frequency range.7Functional Ecology. Insect acoustic communication: The role of transmission channel and the sensory system and brain of receivers
Research in the Amazon has shown that crickets occupy lower and narrower frequency bands than cicadas and katydids. The highest insect acoustic activity occurred in the hours just before sunrise, and acoustic activity was lowest in open pastures compared to forested areas. Canopy cover was positively associated with cricket activity but did not significantly influence katydid activity.8PubMed Central. Time and habitat structure shape insect acoustic activity in the Amazon In a temperate backyard, a similar pattern plays out on a smaller scale: cicadas dominate in hot sunlight, katydids emerge in the evening, and crickets fill in the quieter hours.
Temperature also matters. Crickets are famously temperature-sensitive singers. The snowy tree cricket chirps so predictably with temperature that you can roughly estimate the temperature in Fahrenheit by counting chirps in 13 seconds and adding 40. Warmer air means faster muscle contractions, which means a higher chirp rate. When temperatures drop below a certain threshold, calling stops altogether.
The Dangers of Being Loud
Advertising your location with a loud signal is inherently risky. Predators and parasites have evolved to exploit these calls, turning the mating advertisement into a homing beacon for the caller’s enemies.
One striking example is a predatory katydid in Australia, Chlorobalius leucoviridis, that has learned to mimic the wing-flick responses of female cicadas. When a male cicada calls, the katydid produces clicks and synchronized body jerks that convincingly imitate a receptive female. The male cicada approaches, expecting a mate, and gets eaten instead. What makes this especially remarkable is the katydid’s versatility: it responds effectively to the calls of many different cicada species, including species it has never encountered before.9PubMed Central. Versatile Aggressive Mimicry of Cicadas by an Australian Predatory Katydid
Parasitoid flies are another threat that exploits cicada calls. The fly Emblemasoma auditrix locates its host, the cicada Okanagana rimosa, by homing in on the male’s acoustic signal.10PubMed. Phonotactic flight of the parasitoid fly Emblemasoma auditrix (Diptera: Sarcophagidae) Habitat structure influences how effectively the fly can track its target: the same fly species shows different searching strategies depending on the vegetation surrounding the singing cicada.11Ecological Entomology. Influence of habitat structure on the phonotactic strategy of a parasitoid fly Emblemasoma auditrix Once the fly reaches the cicada, it deposits larvae on or near the host, and the larvae burrow in and consume the cicada from the inside.
How Periodical Cicadas Beat the Odds
Periodical cicadas, the ones that emerge in massive synchronized broods every 13 or 17 years, have arguably the most dramatic solution to the predation problem. By spending over a decade underground as nymphs and then emerging simultaneously in overwhelming numbers, they swamp every predator in the area. Birds, mammals, and reptiles gorge themselves and still cannot make a dent in the total population. Studies have found that predation does not increase as cicada density increases. Estimated predator densities are independent of cicada densities, meaning predators cannot ramp up their numbers fast enough to respond, and the number of cicada wings recovered near bird activity does not significantly increase at higher densities, suggesting that the birds simply get full.9PubMed Central. Versatile Aggressive Mimicry of Cicadas by an Australian Predatory Katydid
This strategy, known as predator satiation, explains why periodical cicada emergences are so spectacularly loud. When billions of individuals emerge in a single region over a few weeks, the collective calling is deafening. Areas with dense emergences have recorded ambient noise levels that make normal conversation difficult. After mating and egg-laying, the adults die within weeks, and the next generation drops to the soil to begin another long underground wait.
Annual cicadas, which emerge every year in smaller numbers, lack this safety-in-numbers advantage. They rely more on individual stealth, camouflage, and the sheer difficulty of catching a fast-flying insect. But their calls are still plenty loud on a per-individual basis.
Other Loud Insects You Might Confuse
Cicadas, katydids, and crickets account for the vast majority of loud tree-dwelling insect noise, but a few other groups occasionally get blamed.
Grasshoppers can be noisy, especially during flight, when some species produce a crackling or snapping sound with their wings called crepitation. Ground-dwelling grasshoppers also stridulate by rubbing their hind legs against their forewings, and researchers have found that grasshoppers living near roads may develop altered sound-producing organs. A study on the grasshopper Glyptobothrus maritimus found that males in roadside habitats had increased stridulatory organs, though the peak frequency of their courtship calls was not clearly elevated along a gradient of noise exposure.12PubMed Central. Male grasshoppers (Glyptobothrus maritimus) in roadside habitats have increased stridulatory sound-producing organs Grasshoppers are less commonly found in trees, so they are unlikely to be the source of overhead buzzing.
Some other insects, like stink bugs and planthoppers, communicate primarily through substrate-borne vibrations rather than airborne sound. A stink bug may drum and vibrate on a plant stem, sending signals that travel through the plant tissue rather than through the air. These signals involve tremulation, percussion, and abdominal buzzing, but they are generally inaudible to the human ear without specialized equipment.13PubMed Central. Tremulatory and abdomen vibration signals enable communication through air in the stink bug Euschistus heros Planthoppers use a rapid elastic-recoil mechanism that does emit some airborne vibration alongside the substrate vibration, but it is far too quiet to be noticed by a person walking under a tree.14PubMed Central. Planthopper bugs use a fast, cyclic elastic recoil mechanism for effective vibrational communication at small body size
Telling Them Apart by Ear
You can usually identify the type of insect just by listening carefully and noting a few clues.
- Cicadas: A sustained, pulsating buzz or whine, often rising and falling in intensity. Heard during the day, especially in hot weather. The sound can seem to come from everywhere at once because multiple males often synchronize or overlap their calls.
- Katydids: A rhythmic, raspy phrase repeated at intervals, typically at night. Some species sound like they are pronouncing their own name. The sound comes from a more specific point in the canopy because individual males tend to space themselves out.
- Tree crickets: A continuous, musical trill that rises in pitch and speed on warmer nights. Often described as the most pleasant of tree insect sounds, with a steady pulsing quality rather than the sharp edges of katydid or cicada calls.
Geographic location helps too. In much of North America, the buzzing you hear in July and August afternoon heat is almost certainly cicadas. The evening and nighttime sounds are a mix of katydids and tree crickets, with field crickets adding a lower-pitched chirp from ground level. In tropical regions, the diversity explodes, and dozens of species may be calling simultaneously.
Do They Damage Trees?
People often worry that a tree covered in cicadas is being harmed. The answer is mostly no, with a small caveat. Adult cicadas feed by piercing twigs and sipping xylem sap, but they do not consume enough to stress a mature tree. The real cosmetic damage comes from egg-laying. Female cicadas slit small branches with a saw-like ovipositor and deposit eggs inside the wood. This causes the branch tips beyond the slits to brown and die, a phenomenon called flagging. On a large tree, flagging is barely noticeable. On a young or recently planted sapling during a heavy periodical-cicada emergence, the damage can be significant enough to set the tree back a season or two. Orchardists and nurseries sometimes cover vulnerable young trees with netting during peak emergence weeks.
Katydids and tree crickets do negligible damage. Some katydids nibble on leaves, but they are not present in large enough numbers to defoliate a tree. The underground nymph stage of cicadas feeds on root xylem for years, but again, the effect on a healthy tree is minimal.
Cicada-Inspired Engineering
The tymbal has attracted attention from engineers and materials scientists because it converts muscular energy into sound with unusual efficiency. Researchers recently developed an artificial rib film inspired by the structure of cicada tymbal ribs. Using a nanoconfined crystallization technique, they created a layered film that achieved a toughness amplification factor twice that of the natural cicada tymbal rib and lasted far longer under repeated stress. When used as an acoustic transducer, the artificial film outperformed commercial polymer films, delivering roughly 2.7 times the frequency response and 2.2 times the displacement amplitude.15PubMed Central. Cicada rib-inspired tough films through nanoconfined crystallization for use in acoustic transducers
This kind of bio-inspired design is part of a growing field that looks to insects for solutions to miniaturization problems. Cicadas pack a remarkably powerful speaker into a body that weighs a few grams. Any technology that needs to produce clear sound from a small, lightweight device faces exactly the same engineering constraints, and the tymbal has had millions of years of natural selection to optimize for that niche.