Science Fun
Voices in the Darkness

Science Standards by State

You will need
  • flashlight


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With the end of summer, and the beginning of school, the sounds of summer - children at the pool, on the playground or at the park - the sounds of people together outdoors, all dwindle.  But there is one group of living things that seems to have been waiting for shorter days and cool, humid nights.  They are the crickets and katydids.  The shorter days, and evenings that are still a bit warm, seem to encourage this interesting group of insects to begin singing.  Their songs are a sort of farewell to summer or a welcome to fall, and they are as interesting as they are hard to see.  Yet it’s worthwhile to listen and to try to see them because they sing in a unique way.

The insects that sing when summer fades into fall are mostly members of a big group called Orthoptera.  “Ortho” means straight, and “ptera” means wings.  The front wings usually are tough, like parchment, and are mostly for protecting the thin, transparent flying wings.  When a grasshopper flies, it lifts up the front wings and holds them out of the way while it uses the thin, transparent hind wings to flap and fly.  If you watch a grasshopper fly in the daytime, you may be able to see how front and hind wings have separate functions.

But it is at dusk or in the darkness of night that the front wings are most noticeable.  Not by seeing them.  But by hearing them.  When a cricket sings, it lifts its front wings and rubs a thickened vein of one wing in the front pair against a file-like vein in the other of the front pair.  If you are careful, slow, steady, and noiseless you may see in the light of your flashlight what most people hear but never see – the source of cricket “songs.”   Cricket-hunting on a warm, moist late summer or early fall evening is not easy.  But it’s challenging and fun!   When you hear a cricket singing, and think you know its location, take a flashlight and step slowly and carefully toward the sound.   When you are close, turn on the flashlight and shine it where the sound seems to be coming from.  You may find the male (females don’t sing) with front wings raised, vibrating one wing’s vein against another, calling an “I’m here!” message to a female.

Some crickets and grasshoppers sing a sustained note, while others sing in bursts, and still others sing in a sort of phrase.  The katydid, for example, seems to sing “katy-did”, “katy-didn’t”, or some variation of that.  And katydids seem to sing from well above the ground, in trees, especially on warm evenings after a rain.

One cricket, called the snowy tree cricket, is pale green, not black or brown like most crickets. It is sometimes called the temperature cricket because its song is correlated to temperature.  It sings from low bushes or trees – a musical phrase repeated over and over again.  If you hear a pleasant pulse of song repeated at a steady frequency, it may be a snowy tree cricket.  If so, count the chirps in 15 seconds, add 40, and that is the temperature in degrees Fahrenheit.  Try it, and you’ll be surprised at the accuracy of this “temperature cricket.”  You may need a flashlight, though, because the snowy tree cricket doesn’t sing until it’s nearly dark, and you may not be able to see the time on your watch.  

Once I needed a picture of a cricket singing, but it was difficult to find one in the daytime.  And all I had was a flash camera.   A cricket was singing just inside the exit hole of a drain pipe.  But unless he came out into the open, I couldn’t take his picture.   So I recorded his song on a tape recorder, then played it back to him.  Apparently he thought the song came from a rival cricket, and out he came, ready to fight.  I got the picture I wanted!

Cricket songs are fun to hear.  And if you are quiet, sneak along carefully and slowly, you often can find the songster.  Sometimes you can find both a male and a female – the male by sneaking quietly toward the song-maker, and the female because she was attentive to, and attracted by, his song.

Spend some time on a quiet, humid late summer or early fall evening, listening to and stalking insect songsters.  You will learn a lot about one of a large and important group of insects – the Orthoptera – a group that includes crickets, katydids, and song-less preying mantises.  They don’t sting or hurt you, and they’re not poisonous.  But their songs are fascinating, especially if you get to see as well as hear them!