Cricket

The chirp

A male cricket’s chirp is produced by stridulation — rubbing one wing across the other. The right forewing has a hardened “scraper” along one edge; the left has a comb-like ridge. Drawing the scraper across the ridge produces a clear chirp, repeated rapidly.

Different chirp patterns serve different functions:

• Calling song — long-distance, attracts females.
• Courtship song — softer, played close to a female.
• Aggression song — territorial warning to rival males.
• Triumph song — after winning a fight.

Both the song’s pitch (carrier frequency) and the chirp rate are species-specific identifiers.

Dolbear’s law

A surprising finding: cricket chirp rate is closely correlated with temperature. The number of chirps per minute increases linearly as temperature rises, because the muscle reactions that drive stridulation accelerate with heat. Amos Dolbear formalized this in 1897 with what’s now called Dolbear’s law:

Temperature in °F = 50 + (chirps in 14 seconds)

Within their normal active temperature range (10–35 °C), it’s accurate to within a degree or two. You can literally calibrate a thermometer with a cricket.

Hearing in the legs

Crickets hear through tympanal organs — eardrums — located not on the head but on the front legs. Each leg has a small slit-like opening that admits sound to a thin membrane stretched over an air sac. They can detect very faint sounds and discriminate frequencies finely enough to distinguish their own species’ song from background noise.

A protein crop

Acheta domesticus is the most commonly farmed insect for human food. Cricket flour — dried, milled cricket — is incorporated into protein bars, baking mixes, and other products. The case for crickets as a protein source:

• About 60–70% protein by dry weight.
• Roughly 1/12 the water and 1/4 the feed of beef per gram of protein.
• Lower greenhouse gas emissions than livestock.
• Can be raised vertically in small spaces.
• Naturally low in pathogens that affect humans.

The challenge is cultural acceptance more than biology — most Western consumers are reluctant to eat insects. Asian and African food cultures have eaten crickets for millennia.

A symbol of luck

Cricket symbolism is positive in many Asian cultures:

• China — keeping crickets in small ornamental cages was a noble pastime; cricket-fighting is an ancient sport.
• Japan — singing crickets are auctioned, kept for their songs.
• Italy — Pinocchio’s “Talking Cricket” is the conscience character (Disney’s “Jiminy Cricket”).

In folklore across Europe and the Americas, a cricket on the hearth brings luck — and killing one brings misfortune.