What's That Sound?

—Allison Bedosky, Education Director

Cicada. Photo Source: kids.nationalgeographic.com

For the past few weeks, beneath the rattling of your air conditioner, you may have heard a maraca-like sound coming from the trees. After a couple of seconds, the shaking fades to a long, continuous buzz. This "song", which can reach up to 85 decibels, is the mating call of cicadas. These insects emerge from underground either periodically or annually. Periodic cicadas come out every thirteen to seventeen years, while annual cicadas emerge after two to five years beneath the soil. Although the loud sound can be deafening at times, it is one of summer's hallmark noises.

In the northeast, July, with its warmer temperatures and light rain, triggers the cicadas' emergence from the ground. Once above ground, life moves to the fast lane for these insects. The young nymphs climb into the canopy of trees and within an hour, shed their skins and enter adulthood. Ten days later, mating begins. Males tend to be the noisiest. The sound is made from the contractions of their tymbals - the grooved exoskeleton on their torsos. Females can lay up to 400 eggs, and these will hatch in six to eight weeks. Once hatched, these nymphs drop into the soil and, the wait to come out again starts all over.

Cicadas usually become more active in warmer temperatures, which explains why they were extraordinarily loud this past month when thermometers were reaching close to 100 degrees Fahrenheit. Enjoy this summer soundtrack now though. The periodical brood we currently hear won't come out again until at least 2030.