The chirping you hear on a summer night is almost always a male cricket advertising for a mate. Females have no song of their own and use his chirps to find him in the dark.1PubMed Central. Silent night: adaptive disappearance of a sexual signal in a parasitized population of field crickets
Why Male Crickets Sing
Only males chirp because only males have the equipment: a wing scraper and a row of teeth, which females lack. A silent cricket in your house is most likely a female or a young cricket that hasn’t matured yet.
The song works as a beacon that also names the species. Each species has its own steady, repeatable long-distance song, which helps females recognize their own kind.2Bioacoustics. Similarities and differences in structure and information content among calling song, courtship song and aggression song in Acheta domesticus crickets (Orthoptera: Gryllidae) Females are tuned to a particular pitch and prefer songs close to it over higher or lower ones.3PubMed Central. Matched Filters, Mate Choice and the Evolution of Sexually Selected Traits A song at the wrong pitch can be passed over even if it is loud. That is how several species can sing in the same field while each female answers only her own kind.
When she does hear the right song, she walks or flies toward it, steering as she goes. If several males are singing nearby, she compares them and picks the more attractive one.
Chirps also carry clues about the singer himself. Larger males tend to sing louder and at a lower pitch than small males.4PubMed Central. Calling, Courtship, and Condition in the Fall Field Cricket, Gryllus pennsylvanicus In house crickets, the number of pulses in each chirp is one of the best clues to size, and female house crickets prefer the chirps of larger males.5PubMed. Female house crickets, Acheta domesticus, prefer the chirps of large males Pulse count, loudness and pitch are clues that can be weighed together. Chirp speed is the least reliable of them, since small male field crickets can chirp faster than large ones.6PubMed Central. Calling, Courtship, and Condition in the Fall Field Cricket, Gryllus pennsylvanicus Speed also depends partly on temperature, so it says little about size on its own.
How a Cricket Makes the Sound
Crickets make sound by rubbing their hardened front wings together. A hard edge on one wing, the scraper, sweeps along a row of tiny teeth on the other wing.7PubMed. Mechanical phase shifters for coherent acoustic radiation in the stridulating wings of crickets: the plectrum mechanism Each tooth struck makes the wing vibrate rapidly, and that vibration is the sound.8PubMed. Sound radiation and wing mechanics in stridulating field crickets (Orthoptera: Gryllidae)
Many people think crickets rub their legs together, but that is grasshoppers. Watch a singing cricket and you’ll see its wings raised and shivering while the legs stay still.
The wing works like a tuned instrument. Its thin cells and veins resonate at the rate the teeth are struck, which amplifies the sound.9PubMed. Mechanical phase shifters for coherent acoustic radiation in the stridulating wings of crickets: the plectrum mechanism A built-in catch lets the scraper pass one tooth at a time, producing one clean sound wave per tooth.10PubMed. Mechanical phase shifters for coherent acoustic radiation in the stridulating wings of crickets: the plectrum mechanism That is why cricket songs sound like a pure, musical tone,11The Orthopterists’ Society. Why Do Crickets Chirp? The Science Behind the Sound while katydids and cicadas sound buzzy or whiny because their tones are higher and less pure.12The Orthopterists’ Society. Why Do Crickets Chirp? The Science Behind the Sound
The separate beeps you hear come from the wing motion. Each chirp is a burst of several pulses, and the loud pulses are made as the wings close, not as they open.13PubMed. Wing movements underlying sound production in calling, rivalry, and courtship songs of the cricket Gryllus bimaculatus (DeGeer) Between chirps the wings open silently. The rhythm of pulses and gaps is part of what makes each species distinct.
Some crickets add tools. Tree crickets chew a hole in a leaf and sing through it, using the leaf as a sound board.14eLife. Tree crickets optimize the acoustics of baffles to exaggerate their mate-attraction signal A well-made leaf baffle on a large leaf can make a male up to about four times louder in effective area, roughly 12 decibels.15eLife. Tree crickets optimize the acoustics of baffles to exaggerate their mate-attraction signal
Three Different Songs and What They Mean
Each song is built for a different audience. The calling song is the loudest and most regular, made to carry far and identify the species.16Bioacoustics. Similarities and differences in structure and information content among calling song, courtship song and aggression song in Acheta domesticus crickets (Orthoptera: Gryllidae) Once a female is close, the male switches to a courtship song, the quietest and most variable of the three.17Bioacoustics. Similarities and differences in structure and information content among calling song, courtship song and aggression song in Acheta domesticus crickets (Orthoptera: Gryllidae) When another male intrudes, he uses an aggression song that sits between the two in loudness.18Bioacoustics. Similarities and differences in structure and information content among calling song, courtship song and aggression song in Acheta domesticus crickets (Orthoptera: Gryllidae) Calling and rival songs use the same wing motion, while courtship uses a different one that adds sharp high ticks.19PubMed. Wing movements underlying sound production in calling, rivalry, and courtship songs of the cricket Gryllus bimaculatus (DeGeer) Because the wing motion changes, courtship is a different performance, not just a quieter version of the same chirp.
The rival song tells another male to back off. If it doesn’t settle matters, males may escalate to physical fights, so the song works as a warning before a fight.
You can learn to tell the songs apart by ear. A soft, irregular ticking near a female is likely courtship. Sharp, rapid bursts when two males meet likely signal a dispute. People who keep pet or bait crickets often notice the change: put two males in a container together and they may suddenly switch to rivalry songs, while a male and female together may prompt courtship.
Some messages travel through the ground. Singing also shakes the surface the cricket stands on, and females use these vibrations along with the sound to find and recognize him.20PubMed. Vibrational signalling, an underappreciated mode in cricket communication At close range, males tremble or drum their bodies on the ground during courtship and fights.21PubMed. Vibrational signalling, an underappreciated mode in cricket communication
Why Crickets Chirp at Night and Faster When It’s Warm
Crickets have a built-in daily clock that keeps their singing on a roughly 24-hour cycle even in steady dim light.22Physiological Entomology. The role of ocelli in circadian singing rhythms of crickets Light still resets the clock each day so the singing stays in step with real sunset, but a cricket kept indoors under steady dim light still chirps in a daily pattern. Some field crickets sing in two bursts, one starting a few hours before dusk and another in the second half of the night.23Journal of Insect Physiology. Circadian control of singing in crickets: Two different pacemakers for early-evening and before-dawn activity Darkness also lowers the risk of being seen while singing.
Warmth speeds up the chirping. Crickets are cold-blooded, so their muscles work faster when the air is warm, and chirp rate rises with air temperature in crickets and their relatives.24PubMed Central. The effects of temperature on chirp-rate of male cone-headed grasshoppers, Neoconocephalus ensiger Counting chirps can therefore give a rough temperature. A common version for field crickets is to count chirps in 14 seconds and add 40 to get degrees Fahrenheit. Pick a single cricket rather than a chorus.
Results are rough and vary by species. The trick works poorly below about 55°F, when crickets slow down or stop.
If you walk toward a chirping cricket, it often goes quiet. Footsteps and vibrations alert it, and stopping makes it harder for predators to locate it. It resumes once things are quiet again.
How Crickets Hear the Song
A cricket’s ears are small membranes on its front legs, just below the knee.25PubMed Central. Hyperacute Directional Hearing and Phonotactic Steering in the Cricket (Gryllus bimaculatus deGeer) The legs stick out to the sides and are spaced apart, which gives the cricket two separate listening points.
Sound reaches each eardrum from outside and from inside, through air tubes that open on the sides of the body.26PubMed Central. Diversity of acoustic tracheal system and its role for directional hearing in crickets A tube connecting the two ears lets the cricket compare sound arriving at each side.27PubMed Central. Diversity of acoustic tracheal system and its role for directional hearing in crickets Because sound arrives by two routes, the eardrum’s vibration depends on where the sound comes from. The cricket compares how strongly each side responds and turns toward the stronger one. The result is that crickets can tell very precisely which direction a song is coming from.28PubMed Central. Hyperacute Directional Hearing and Phonotactic Steering in the Cricket (Gryllus bimaculatus deGeer) People are far worse at this; a cricket’s pure tone is hard for human ears to locate.
The Cost and Danger of Chirping
Singing takes real energy. A calling field cricket uses nearly three times the oxygen it uses at rest.29Physiological Entomology. The energetic cost of calling in the variable field cricket, Gryllus lineaticeps Faster chirping uses more energy, yet females prefer faster chirps in some species.30Physiological Entomology. The energetic cost of calling in the variable field cricket, Gryllus lineaticeps So the most attractive songs are also the hardest to keep up. A male that sings hard for hours has less energy left for feeding and growing.
There is also a more deadly risk. A parasitic fly found in North America homes in on singing male field crickets.31Animal Behaviour. Host song selection by an acoustically orienting parasitoid fly exploiting a multispecies assemblage of cricket hosts It drops live larvae on and around the cricket.32Florida Entomologist. Success of the Parasitoid Fly Ormia ochracea (Diptera: Tachinidae) on Natural and Unnatural Cricket Hosts The larvae burrow in, feed on the cricket, and later emerge to pupate, killing their host.33PubMed Central. The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea
Some crickets evolved to go silent. On the Hawaiian island of Kauai, a wing mutation that makes males unable to chirp spread to more than 90% of males in under 20 generations.34PubMed. Rapid evolutionary change in a sexual signal: genetic control of the mutation ‘flatwing’ that renders male field crickets (Teleogryllus oceanicus) mute Silent males escape the fly, which finds hosts by sound.35PubMed Central. Silent night: adaptive disappearance of a sexual signal in a parasitized population of field crickets They find mates by staying near the few males still singing and intercepting females.36PubMed Central. Silent night: adaptive disappearance of a sexual signal in a parasitized population of field crickets In one population the mutation eventually took over completely and the crickets went silent.37PubMed Central. Temporal genomics in Hawaiian crickets reveals compensatory intragenomic coadaptation during adaptive evolution Silence only spreads where the parasite is common; elsewhere, singing pays off more than it costs.
How Traffic Noise Changes Cricket Songs
Tree crickets near busy roads sing shorter bursts when traffic is loud, and they pause more often as noise rises.38Animal Behaviour. Instantaneous song modification in response to fluctuating traffic noise in the tree cricket Oecanthus pellucens Unlike some birds and frogs, they don’t shift their song to be heard over the noise.39Animal Behaviour. Instantaneous song modification in response to fluctuating traffic noise in the tree cricket Oecanthus pellucens Field crickets living near highways chirp faster, especially when rival males are nearby.40PubMed Central. Traffic noise exposure impacts song production in wild male field crickets (Gryllus bimaculatus) under predator and intrasexual competition contexts Insects can’t simply sing louder, since their volume is limited by wing size, and changing pitch would make the song unrecognizable to females.
Crickets Kept for Their Song
People in China began keeping crickets for their songs in ancient times.41Wikipedia. Crickets as pets Fanciers chose crickets with the best voices and matched them to gourd cages with the right acoustics.42JSTOR Daily. Keeping Crickets for Luck, Song, and Bloodsport In Florence, Italy, crickets were given as gifts on Ascension Day, and a chirping cricket meant good luck for the year.43JSTOR Daily. Keeping Crickets for Luck, Song, and Bloodsport
If you want to keep a singing cricket today, remember that only adult males sing. Keep it warm for more frequent chirping, and keep males apart to avoid fighting songs and fights. Darkness and quiet encourage calling.
If you’d rather get rid of one chirping indoors, move slowly and pause when it stops. Turn the lights off and listen from different spots in the room. Then catch it under a cup and release it outside.