Friday, August 7, 2015

The Noises of August by Donna Duffy

Cicada, photo courtesy CSU Extension

You’ve probably noticed that it's a noisy place out in the backyard with all that insect racket going on. Interestingly, only a few groups of insects communicate by rubbing their body parts together. What you are hearing are most likely cicadas, crickets and katydids. As you might suspect, it’s the males making all that commotion!

Cicadas are among the largest Colorado insects. Twenty-six different species exist in the state, and the largest are stout-bodied insects over 2 inches long. Despite their size and abundance, they cause little injury to plants and control isn’t necessary. The adults are only present for about 4-6 weeks after they emerge. You’ll hear their chorus in the late afternoon with the ascending zing-zing-zing sound coming from trees. You are much more likely to hear the cicadas than to see them, though you may notice the empty shells they leave on tree trunks and fence posts as they transform to the winged adult stage. Legend has it that the first cold snap will come about 6 weeks after the cicadas start their chorus.

Field cricket, photo courtesy CSU Extension

But cicadas aren’t the only noise-makers in your yard. At dusk the male crickets begin rubbing their wings together, dragging a small peg on one wing across a row of ridges on the other.  The result is a series of clicks similar to what happens when you click your thumbnail down the teeth of a comb.  Only with the crickets the clicks are so fast you don't hear the individual clicks. What you hear is a trill or a chirp.  The black field crickets are the ones you’ll see in your garage and house later in the fall, so their sound is probably familiar to you.  The tree crickets produce short, perfectly-spaced trills that you hear from a distance all summer long.

Katydid, photo courtesy CSU Extension
 Late at night the last singers of the day take over and sing till the wee hours of the morning.  Katydids are large green insects (2 -2 1/2 inches in length) that resemble a leaf and easily hide within the upper crown of a hardwood tree.  They are named for the rhythmic song they sing in late summer.  The males sing in quick bursts of two, three or four notes that sort of sound like Kay-tee-did.  Or Kay-tee-did-did.

The songs of the insects grow slower and slower as temperatures decrease, and they eventually fall silent by October.  Alas.  Enjoy the chorus while you can!

Note: Thanks to Donald Lewis, Extension Entomologist from Iowa State University for sharing this information.