How Does A Cicada Know When It Is Time To Leave its Underground Dwelling?

20108339 - 17 year cicada (magicicada) perched on a stick with a green background

Cicadas are amazing creatures, as they don’t ever seem to get sick of dirt. Which other insects do you know of that can live underground for a shade under two decades? But there is one aspect of the cicada that begs an important question, how do cicadas know when to leave the ground in order to start an above ground life?

According to Chris Simon, a professor in the Department of Ecology and Evolutionary Biology at the University of Connecticut, cicadas posses an internal clock that keeps track of the time that cicadas have spent underground. A periodical cicada is likely sensitive to environmental cues that indicate the best time for the cicada to leave its belowground home. To be more specific, these signals could be telling the cicadas that a full year has passed. When the trees that cicadas use for sap begin to leaf-out. This event changes the composition of fluid in tree routes. The altered fluid from tree routes occurs once a year, and the new fluids are ideal for nymphs. Nymphs will drink this fluid in order to develop properly.

Once the cicadas are out of the ground they indulge in a frenzied mating period that lasts four to six weeks. According to the U.S. Department of Agriculture, female cicadas will lay eggs three to five days after mating. Females typically lay around twenty five eggs, or more, and after six weeks, these eggs will hatch. Then the nymphs will burrow underground, thus allowing the whole process to start again. Once these nymphs reach adulthood and leave their underground homes, it will be seventeen years into the future in 2034. Whether you find the sound of cicadas annoying, or pleasant, there is no doubting that cicadas are one of nature’s stranger insects.

Have you ever learned of a cicada presence within your home, but been unable to locate the insect despite its loud call?