Beginning last Friday night, I have been hearing the enchanting sound of the snowy tree crickets chirping in the Waconia, Minn., area.
Other observers in Golden Valley and Northfield reported first hearing these night singing insects the very same evening. Late summer nights are the best time. The insect population is at its height and most of the individuals have reached their maturity, so by 9 p.m. the activity of the various singing insects is in full swing.
The snowy tree cricket, a relative of the black field cricket, is also called the temperature cricket because it’s a rather accurate thermometer. This cricket chirps more times per minute when it is warm than when the air is cool. To produce their music, the males raise their wings straight above their backs, rubbing them together.
The vibration creates a chirp with a shrill tuneful and persistent “chee-chee-chee,” also described as “treat-treat-treat.” It’s a sleigh bell-like sound. If you count the number of chirps in 15 seconds and add 40, you will have a good approximation of the air temperature in Fahrenheit.
I counted 47 chirps in 15 seconds from a snowy tree cricket Friday night. I added 40, for 87 degrees. A nearby thermometer also read 87.
Looking carefully with a flashlight into a shrub you may catch sight of this shy, pale-green creature hardly an inch in length. The melodious night music has been described as “the sound of moonlight.”
Jim Gilbert’s Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. He is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.