CRICKETS ARE GETTING COLD

It wasn't a few days ago I was sitting out in my backyard, the sun had long gone down and a funny thing was happening. It was completely silent. I couldn't help but think of that movie "Arachnophobia". Did a horde of deadly spiders make it into my town from some Venezuela jungle and wipe out every living thing? Was I next? Well I rushed to the phone and dialed the University Entomology department and asked for the head guy in charge...he was on expedition...none of this is true except the part where i was listening to a dead silence in my backyard at night a few days ago. It was strange. Usually the metallic chattering of the summer canopy had started in full chorus. I wondered. Two nights ago i noticed...BOOM!! The orchestra had begun and summer had finally dug in.

Dolbear's Law states the relationship between the air temperature and the rate at which Snowy Tree Crickets, Oecanthus fultoni, chirp. It was formulated by Amos Dolbear and published in 1897 in an article called "The Cricke tas a Thermometer". Dolbear expressed the relationship in his formula which provides a way to estimate the temperature in degrees Fahrenheit from the number of chirps per minute.

Subsequently the following article just appeared in The New York Times":

It is very likely that the silence was related to cool summer nights, said Gary W. Felton, a professor of entomology and the head of the department at Pennsylvania State University. The situation has probably changed with recent warmer weather, he said.

“I don’t know what the temperatures have been like in the Philadelphia area, but in State College it has been a very cool summer, abnormally so,” Dr. Felton said. “Two weeks ago, I commented that we usually have a lot of tree frogs at night, but I had heard nothing. But now they are doing quite well. I suspect that is also temperature-related.”

In frogs and crickets, Dr. Felton said, the development period depends on temperature. “And there has been nothing sprayed on a wide basis that I know of,” he said, “so the most likely explanation is simply a cool summer.”

Cricket metabolism and chirping speed vary with ambient temperature, and the speed also varies by species. The snowy tree cricket is so dependable that a formula called Dolbear’s Law (after the physicist A. E. Dolbear, who reported his studies in 1897) provides a temperature gauge: count the number of chirps in 15 seconds and add 40 for the temperature in Fahrenheit.