This month, billions of insects called cicadas will swarm the Northeastern U.S. The grasshopper-like, red-eyed bugs with black-and-orange bodies have spent the past 17 years underground. They’ll emerge for about a month to reproduce before dying off. During that time, people living in the area might want to buy some earplugs, because cicadas are known for making quite a racket.
Male cicadas use vibrating membranes, called timbals, on their abdomens to produce a loud buzz that attracts females. Though the noise might be appealing to cicadas, many people say the sound resembles a chorus of chainsaws.
Cicadas have an unusual life cycle (which is the series of changes in the life of an organism). After cicadas mate, the females lay their eggs on trees. When the eggs hatch, the immature insects, known as nymphs, burrow into the soil below. There they feed on plant roots until the bugs are mature.
The length of time the insects remain underground depends on the species, of which there are about 1,500. Some types, called annual cicadas, come out of the ground within a year of hatching. The more famous kind, called periodic cicadas, take much longer—either 13 or 17 years. The bugs emerge from the ground to reproduce, often in large groups called clouds or plagues. In some areas, there may be as many as 1.5 million cicadas concentrated in a single acre!
How do cicadas know when to emerge from their underground homes? Scientists aren’t sure. They do know that during cicadas’ last year of life, the insects wait until the soil temperature reaches 18°C (64°F) about 20 centimeters
(8 inches) below the ground before heading for the surface.
Although many people consider cicadas to be a nuisance, anticipation of their arrival in the Northeast is building. In Ohio, where large numbers of the bugs are expected, festivities are being planned around the milestone.
“There’s lots of cool biology elsewhere in the world, but this is something happening here that is really remarkable and unique to this region,” Gavin Svenson, an entomologist (a scientist who studies insects) and a curator at the Cleveland Museum of Natural History in Ohio, recently told the newspaper The Plain Dealer.