You know that warm weather is really here when you hear that first cricket, chirping alone in the dusk some evening in late spring.
He, (definitely a male), is rubbing his wings together to make a sound called stridulation in a strenuous effort to attract a mate. The pattern of his call advertises his species to the female cricket, and the speed of his chirping gives a rough indication of the evening air temperature.
Crickets are cold-blooded; they get sluggish when cold and so their chirping is slow when the night air is cool. But females are attracted to louder, faster chirping males, so the male cricket works as hard as he can and as fast as the temperature will allow.
The chirping rate of one species, the snowy tree or “thermometer” cricket, has been found to correlate very well with temperature. Our western cricket is not as accurate, but does speed up when it’s warm. You won’t hear them at all until the evening temperature is greater than 55 °F.
In Sonoma County, the cricket that you hear is probably a Variable Field Cricket with the scientific name Grillus lineaticeps. Until the 1950’s, all crickets in the United States were thought to be the same species. It turns out that they are not the same, and that species can be differentiated partly by the pattern of their chirping.
Does the cricket in your back yard sound like this? (May be more than one cricket in recording.)
If not, it may be one of these other species, which are not so commonly found in Sonoma County.
In the wild, crickets live in cracks or burrows in the ground, in meadows and on the edges of forests, eating seeds, leaves, and smaller insects. They’re also a beneficial ‘clean-up’ insect and consume dead plant and animal material. Female crickets like damp soil in which to deposit their eggs, so to a male cricket a suburban lawn is a great place to be in early summer. This is why we hear them close by from our back porch or through an open window.
When we first hear them in late spring, they’ve just come into adulthood, having hatched in early May from an egg which overwintered in the ground. The just-hatched cricket is a nymph, which looks like a tiny adult cricket. If the nymph manages to avoid predators by staying nocturnal, using camouflage, and hiding in burrows, it grows very quickly into an adult in about 6 weeks.
Sadly for the adult cricket, the chirping meant to attract a female can also attract a parasitic fly, Ormia ochraea, whose hearing is genetically tuned to a cricket species’ particular patterns and frequency of chirps. When O. ochraea finds a cricket, it deposits eggs on it, and when the eggs hatch they burrow into and eat the cricket host. The parasitic fly is one of a long list of the cricket’s predators: birds, frogs and toads, spiders, snakes and even some mammals.
So enjoy the summer evenings, and listen to the cricket, chirping as loud and long as he can to attract a mate in spite of the many enemies listening and looking for him.