Earth Almanac: September/October 2006

Wing Song

In most of the contiguous states save parts of the extreme Southeast, there is a magical night in late summer when the snowy tree crickets start their concert. Suddenly it breaks forth from backyard shrubs, vines, and trees—melodious, regularly spaced chirps that blend to a trill as the males rub together the rough edges of their wings. Nathaniel Hawthorne described it as “audible stillness,” observing that “if moonlight could be heard, it would sound just like that.” The warmer the night, the faster the tempo; so precise is the variation, in fact, that you can calculate air temperature in Fahrenheit by counting the number of chirps for 15 seconds and adding 40. An internal “antifreeze” called glycogen allows snowy tree crickets to prolong Indian summer with their haunting music through the first few killing frosts.