Invertebrates
Cricket
Gryllidae · also called true cricket
The chirp of a cricket on a warm evening is one of the most familiar sounds in nature, and one of the few that comes with instructions: count the chirps, do a little arithmetic, and you have the temperature. Crickets are long-antennaed, mostly nocturnal insects, and their males have turned their own wings into a musical instrument.
Overview
Crickets are the family Gryllidae, with roughly 2,400 species. A cricket has long, thread-like antennae, a flattened body, hearing organs on its front legs, and, in the female, a long needle-like egg-laying tube. Most are nocturnal omnivores, eating plants, fungi, decaying matter, and other insects, and they live on grassland and forest floor, in caves and deserts, and around and inside human buildings, on every continent but Antarctica.
The song
Only the male sings, by drawing a scraper on one forewing across a file on the other, with a membrane amplifying the sound. The song attracts females and warns off rival males. Because a cricket is cold-blooded, its chirp rate rises with temperature, and for the snowy tree cricket a rough rule holds — count chirps in 13 seconds and add 40 for the temperature in Fahrenheit.
From feeder insect to flour
The house cricket is raised in huge numbers as food for pet reptiles and birds, and increasingly for people, dried whole or milled into a protein-rich flour promoted as a lower-impact alternative to meat. In China, crickets have been kept for centuries in cages for their song, and historically matched in staged fights.
Status
Crickets as a group are Not Evaluated. Most are common, but some species confined to single caves or islands are threatened by habitat loss and introduced predators.
Cricket: common questions
What is the difference between a cricket and a grasshopper?
Both are in the order Orthoptera, but crickets and their relatives sit in one suborder and grasshoppers in another. A cricket has long, thin antennae, usually as long as the body or longer, a somewhat flattened body, hearing organs on the front legs, and it sings by rubbing its two forewings together, with only males singing. Grasshoppers have short antennae, a more cylindrical body, ears on the first segment of the abdomen, and they make sound by scraping a hind leg against a wing. Crickets are mostly active at night and are often dark brown or black; grasshoppers are mostly active by day and are often green or straw-coloured. The female cricket also carries a long needle-like egg-laying tube that a grasshopper lacks.
Why do crickets chirp, and why do they stop when you come near?
The male's chirping is mainly an advertisement to attract females, who move toward a calling male, and a slightly different, harsher song is used to warn off rival males, while a soft, rapid courtship song is given close to a female. The rate and pattern are species-specific, so females can pick out their own kind. Crickets fall silent when they detect a large approaching animal because the vibration and sound of footsteps signal a possible predator, and going quiet and still makes the cricket much harder to locate. Wait motionless for a minute or two and the singing usually resumes.
Can a cricket really tell you the temperature?
For some species, yes, roughly. A cricket is cold-blooded, so the muscle contractions that drive its song speed up when it is warm and slow down when it is cool, and the chirp rate tracks air temperature fairly closely. The best-known rule, sometimes called Dolbear's law, applies to the snowy tree cricket of North America, where you count the number of chirps in 13 or 14 seconds and add about 40 to get the temperature in degrees Fahrenheit. Other crickets follow their own version of the relationship. It is a genuine effect, though the exact numbers vary with species, humidity, and the individual insect.
Are crickets good or bad to have around?
Outdoors, crickets are a normal and useful part of the ecosystem, feeding on plant debris and small insects and providing food for birds, lizards, spiders, and small mammals, and their song is for many people a pleasant sound of summer nights. Indoors, a field or house cricket that gets inside is mostly a minor nuisance, keeping people awake with its chirping and occasionally nibbling paper, fabric, or stored food, but it does no real harm and is easily removed or ignored. Large infestations, usually of house crickets escaped from breeding operations or attracted to lights in warm regions, can be more of a problem and may need the usual measures of sealing gaps and reducing outdoor lighting.