Singing crickets, cicadas and katydids

Wednesday September 19, 2012

Green leaves are fading, and some are starting to turn red. Children and teachers are heading back to school. Many signs tell us that the seasons are changing. Some of those clues are the prominent sounds of crickets and grasshoppers as they perform their late summer swan song.

Spring is usually thought of as the time for courtship and reproduction, but for crickets and grasshoppers, now is when mating and egg-laying occurs. That is why we hear their calls, mostly created by the males, as they attempt to attract females and intimidate competitors.

The sounds, like bird songs, are specific to each species. When a male calls, the female of his kind will respond and approach him. After mating occurs, she deposits her fertilized eggs in the ground, or sometimes in plant material, where they will remain for the winter. In the spring (or summer, depending on the species,) the eggs will hatch and begin to grow. Cricket nymphs (juveniles) go through eight to 12 molts over a period of up to 90 days, until they are mature.

But that's all for another time.

What is going on right now is a regular song fest. The crickets and grasshoppers, including some of the long-horned grass hoppers that we call katydids, make their music using their wings. One of the wings has a series of ridges, like a file, and it rubs against the other wing, which has a scraper. The chirps, buzzes and trills are created by the variations of this rubbing and the vibrations that result. It is similar to what happens when you run your finger across a comb.

Learning to distinguish the different sounds can be quite interesting. If you hear a musical whistle with a distinctive pitch (one that you could perhaps imitate with a hum or whistle), it is being made by a cricket.

Grasshoppers make a more mechanical sound, like that of sandpaper being rubbed together.

The katydid calls at night with a nasal sound that seems to be saying, "katy-did, katy didn't."

Who makes up the chorus depends on whether the concert is during the day or at night. During the daytime, you may hear another type of insect, the cicada, which contract abdominal "tymbal" muscles to make their sounds. They create a high-pitched, long, whining sound, one of the loudest of any insect.

Within the cricket group, there are further distinctions. Snowy tree crickets are rather lacey and pale green. As their name im plies, they are found mostly in trees and shrubs and are hard to see because they blend in with the leaves. They sing primarily at night and have a very regular, high-pitched and evenly spaced chirp that resembles the beeping of a bus backing up.

They are sometimes called the "thermometer crickets" be cause the rate of their chirping is temperature-dependent. As the temperature rises, their chirping increases. If you count the number of chirps you hear in 15 seconds and add 40, it will give you the approximate temperature in degrees Fahrenheit. This trick only works between the temperatures of 45 and 90 degrees, but it is fun to experiment and see how accurate your local crickets are (or how accurate your thermometer is). The slowing ca dence of these calls relative to the declining temperatures will be another sign of autumn.

The crickets that we most commonly see are the ground or field crickets, which are dark brown or black. They too make rhythmic chirps, but they also create the high-pitched, pulsating trills. We can hear their sounds either during the day or at night.

If you find one, make note of its location. The males can be quite territorial and often will stay in the one place for days. If you visit a spot repeatedly, you are likely to encounter the same creature. But don't be surprised if one day he is gone. This is a season of transition, where things are constantly changing.

That's one reason it is great to stop and take notice of all that's going on, because if you don't, you may miss it -- at least until next year.


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