Guess what? You might have a thermometer hiding in your backyard, and it sings! On a summer night, count how many times a cricket chirps in 15 seconds. Add 40 to that number. What you get is a pretty good guess at the outside temperature in degrees Fahrenheit.
How does a bug know how warm it is? It doesn't really know. A cricket's body just warms up or cools down with the surrounding air. When the air is warm, crickets chirp faster. When it cools off, their chirping slows down. So the song's tempo follows the temperature.
Here's a silly detail. Crickets don't chirp with their mouths at all! The boy crickets make that sound by rubbing their front wings together. Every kind of cricket has its own special chirp.
One kind, the snowy tree cricket, does this trick so well that people call it the thermometer cricket. A scientist named Amos Dolbear wrote about the cricket thermometer way back in 1897. People still call the rule Dolbear's law.
The cricket trick isn't perfect, so it's just a good guess. But it sure is more fun than looking at a screen! Next warm evening, grab a timer and go listen.
Question for your kid: If a cricket chirps 30 times in 15 seconds, how warm do you think it is outside?