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Posts tagged “Dolbear’s Law

Chirping Thermometers

The evenly-spaced chirping notes of the male Snowy Tree Cricket (Oecanthus fultoni) greet our ears nightly at this time of year.  Named for its pale color and tendency to be found in trees, vines and shrubs, this cricket is well known for its ability to convey the temperature to anyone who can count the number of chirps it makes in 14 seconds.  Add “40” to this number and you know how hot or cold the evening is in degrees Fahrenheit.  The relationship between the air temperature and the rate at which crickets chirp is called Dolbear’s Law.

Crickets make chirps (stridulate) by rubbing a structure on the top of one forewing wing (scraper) against wrinkles (file) on the underside of the other forewing.  To find a Snowy Tree Cricket that is stridulating, check the underside of branches and leaves.  A living thermometer awaits you there.

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