Many of the bugs of summer are at their peak of population and activity right now. Iowa State University entomologist Donald Lewis says one of the noisiest — is also among the most shy and harmless.

The cicada is an annual performer, and they show up around midsummer and start making their distinctive noise around the middle of the day, up until dark. Lewis says many people confuse those with another cricket-like bug, which works a later shift.

The katydid’s sound is much different, harsher and more “clacky,” he says. Both are in great abundance right now, putting on what Lewis calls a “spectacular display of sound.” Lewis says despite the racket, it’s hard to find them.

More people are familiar with the cicada, a bug about as big around as your finger and about an inch-and-a-half long with a greenish color, black highlights, and “cellophane wings.” The katydid’s a type of grasshopper and most people will notice the resemblance though it’s bright green and very tall. With both cicadas and katydids, Lewis says it’s only the male of the species making all that noise.

Even though they’re good-sized, he says the insects work to draw more attention to themselves — at least from female insects, so they use their wings to amplify their sounds and make them even louder. Still, when the weather turns cold Lewis says they’ll be all gone once again.