What are crickets communicating when they chirp?

Have you ever walked across a field and thought to yourself, “what is that incessant noise?” 

Well, those are crickets chirping away letting their potential mate know where they are. 

The chirping noise, however, doesn’t come from their mouths but when they rub their winds, making them produce a resonant and intense vibration.

Although we are used to hearing their “singing” every time we go out into the field, it is difficult to establish the location of a cricket. This is because the wavelength of their song is similar to the distance between two human ears. On the other hand, the female cricket captures this sound because she has a particular kind of eardrum, like most insects of the Orthoptera family, which are designed to interpret these chirps in an intended way.

Cricket in its burrow/iStock.

Even though it appears that the chirping also allows the female cricket to determine whether or not its male suitor is a large one, the singing is not only dependent on size. Tiny, almost transparent and very rare, tree crickets are capable of changing the pitch of their song with temperature.

One particular species, the Oecanthus henryi, sings with a high, squeaky 3.6 kilohertz (kHz) pitch when the temperature outside is 27 degrees Celsius, while that same song becomes a deep bass of 2.3 kHz if the temperature is 18 degrees Celsius.

As the wings of these insects get longer, the frequency and amplitude of the different modes of vibration get closer and begin to merge with each other. The frequency of the song of these animals is not related to their size, but to the speed at which the tree cricket is able to move its wings.

Given that they are cold-blooded animals, temperature influences their activity, so they have more energy and sing faster and at a higher frequency as the temperature increases. Therefore, the cricket's song also contains meteorological information: the sharper it is, the warmer it is.