If you spend time outside during the summer, you have likely heard either a low rhythmic buzzing or a pulsating high-pitched whirring sound coming from the tree tops. Sometimes you might hear both at the same time. Several people have asked me, “What in the world is making all that racket in the woods?”
It’s cicadas and katydids, along with a few crickets chiming in to help round out the summer serenade, day and night. Cicadas make their mating sounds by vibrating scales on their abdomens. Since they don’t eat, the abdomen functions as a hollow sound chamber. It’s loud and a bit discordant, but serves the purpose of attracting a female.
Katydids create their somewhat more symphonic sounds by rubbing their forewings together, producing a repeating series of two to four notes that some people say resembles the phrase, “Katy did, Katy didn’t.” The best way to discern between the two is to listen to one of the many audio clips on the Internet of the two insects.
Two types of cicadas live in our area: annual or dog-day cicadas, and periodical or Brood X cicadas, which are distinguished by their red eyes.
Annual cicadas are present every year, while periodical cicadas only emerge from the soil every 13 or 17 years. There is never any doubt when the periodical cicadas appear. There will be hundreds of them in any given wooded area, all booming out their mating calls at a level that can reach more than a hundred decibels, comparable to a lawnmower or chainsaw. It can get on your nerves if you really focus on it, and the hotter it gets outside, the louder they get. The rhythmic, soothing sounds of katydids, on the other hand, will lull you to sleep if you leave your windows open in summer.
Cicadas have a particularly interesting life cycle. Annual cicadas spend two years living underground in the larval or “grub” phase. Periodical cicadas take a different tack. They remain underground for more than a decade and emerge en masse in a strategy called “predator saturation.” The more cicadas there are, the less chance any individual has of being eaten by a predator.
When cicadas emerge from the soil, they crawl up on some vertical surface: a tree, power pole, fence post or even the wall of a building. A seam along the length of the exoskeleton splits open and the adult cicada frees itself from the shell, then spends an hour or so completing the metamorphosis process. It then crawls up into the treetops and spends the next month or two making a big racket that sometimes annoys us, but is sweet, seductive music to a female cicada looking for mate.
About this time last year, I was down at our garden and witnessed this impressive event firsthand. I watched in awe as a cicada nymph climbed about 1 foot up the base of a big poplar tree, halted and emerged as a beautiful aquamarine colored adult. I ran back to the house, grabbed my camera and was able to capture a few photos of the freshly emerged adult cicada.
Dennis Chastain is a Pickens County naturalist, historian and former tour guide. He has been writing feature articles for South Carolina Wildlife magazine and other outdoor publications since 1989.
