Cricket Thermometer

Un-mowed fields and "waste places" are considered unproductive in terms of bales of hay produced, but they are teeming with insects. Ants, butterflies, moths, spiders, grasshoppers and crickets thrive beyond the realm of lawnmowers.

Worldwide, there are 900 species of crickets. Often confused with grasshoppers because they both have long hind legs for jumping, crickets have flattened bodies and long antennae. Green grasshoppers are active by day and brown or black field crickets are nocturnal. The evening chorus of male field crickets is the soundtrack of late summer.

Crickets mate in late summer and lay as many as 2,000 eggs per fertile female in late fall. To attract females, male crickets “stridulate” by scraping one wing against a specialized toothed comb on the underside of the opposite wing. Wing membranes help to amplify and direct the sound. Each cricket species chirps in a characteristic pitch.

The rate of chirping is influenced by air temperature. Insects are cold-blooded. As temperatures rise, the muscle contractions used to produce chirping happen more rapidly. When temperatures fall, chemical reactions influencing muscle contractions slow.

In 1897, Amos Dolbear, perhaps unable to sleep, formulated an estimate of the temperature In Fahrenheit by counting cricket chirps. Using Dolbear's Law, count the number of chirps produced in 15 seconds and then add 40 to use the cricket thermometer. The chirping of fall field crickets in New Hampshire cannot be precisely correlated to temperature because the rate varies with age and mating success.

In the US, cricket chirping indicates dramatic silence - like at the end of a long and complex monologue which ends with a question… Know what I mean?