August Snowy Tree Crickets
Its snowy tree crickets (Oecanthus fultoni), not Santas reindeer, making the sleigh bell-like sounds on late summer evenings. Snowy tree crickets are slender, delicate looking insects that live you guessed it in trees. (But dont be surprised to find them in shrubs and grasses and just about anywhere else).
The young hatch from eggs in the spring of the year, then go through as many as 12 molts before they reach adulthood in mid-summer. Along the way, the nymphs consume flowers, foliage and young fruit, while adults have a more robust diet of aphids and caterpillars.
Snowy tree crickets are perhaps best known as natures thermometer, because the rate of their chirping correlates well with temperature. The formula (depending on whom you ask) is to count the number of chirps in 13 seconds, then add 40 to find the temperature in degrees Fahrenheit.
To hear a recording of snowy crickets and learn more about them (and the mathematics of chirping), visit the Natural Clocks: Cricket chirps page.