This unusual life history is an evolutionary strategy, according to a 2004 study in the journal Physical Review Letters. Only found in the eastern United States, periodical cicadas develop underground for 13 or 17 years before emerging for their month-long reproductive frenzy and subsequent deaths. (The record for greatest longevity probably belongs to a wood-boring beetle, one of which was found after a 51-year larval stage, according to the University of Florida’s Book of Insect Records.) What does “periodical” mean?Ī periodical cicada, like those in Brood X, is a cicada whose lifespan is based around a prime number - a number that can’t be divided by another whole number. It’s a short adult phase, but periodical cicadas are one of the longest-lived insects in the world. If they’re lucky enough to avoid predators and find a mate, they will reproduce once and then die. Each species produces a distinctive call, likely to help members of that species find each other. Then, according to the Annual Review of Entomology study, cicadas spend four to six weeks arranging themselves in trees, locating others of their own species, and making as much noise as they possibly can. They're extra vulnerable to predators before their new exoskeletons harden and turn from white to black and red. The nymphs will feed at tree roots for a year in the case of annual cicadas, and up to 17 years in the case of periodical cicadas, such as Brood X (the 'X' represents the Roman numeral '10,' and Brood X is one of 12 cicada groups that emerge every 17 years).Ĭicadas emerge from the ground and molt into their winged adult forms. There, they tap into tree roots and feed on the tree’s fluids, which contain few nutrients but allow the cicadas to grow slowly and safely. These juvenile cicadas fall out of the trees where they were born and burrow into the ground below. After hatching, the tiny, wingless nymphs don’t look much like adult cicadas. Like most insects, they have six legs and two sets of wings as adults.Ĭicadas begin their lives as eggs laid by adults high in trees, according to a study published in 1995 in the journal Annual Review of Entomology. The 3,000 species of cicadas found worldwide range from 0.75 to 2.25 inches (1.9 to 5.7 centimeters) long, according to National Geographic.

People should also appreciate that these insects have been around for about five million years, about the time that the ancestors of humans and chimpanzees split from one another, Cooley says.Cicadas are winged insects whose closest relatives are other sap-sucking bugs, like aphids and leafhoppers. ( Learn more: Murder hornet mania highlights dangers of fearing insects.)īut Brood X’s arrival is a chance to change that, Cooley says, by stopping to take a closer look at cicadas and appreciating their long, synchronized life cycles, including their brief, four-to-six weeks of life aboveground. “I think Americans in particular are kind of trained to abhor insects-they don’t have a lot of contact with them and think of them as being dirty,” Cooley says. Fear of insects generally comes from a lack of education and experience, she adds. “They don’t sting, they don’t bite, they’re not going to try to come after you,” Barnes says. “They’re coming out in the biggest orgy that you’ll see in your lifetime,” he says. This phenomenon, and the loud noises they make, is all about procreation, Lockwood adds. But why do they choose such long time periods, which are both prime numbers? There are about 3,000 cicada species on Earth, but only seven are periodical cicadas, which are unusual in that they come out every 13 or 17 years and are almost all found in North America. “You’re taking insect biomass that’s been underground for years and then quickly moving it aboveground-and this has far-reaching positive impacts,” says Elizabeth Barnes, an entomological educator at Purdue Universityīesides being a source of food for predators, the cicadas’ emergence helps move nutrients around the ecosystem, aerate the soil, and relieve predatory pressure on non-cicada insectpopulations, she says. These estimates “are the highest recorded for a terrestrial animal under natural conditions,” the scientists wrote.

One study estimated that the total biomass of cicadas in a given area of forest is greater than the biomass of cattle the same area could support if it were turned into pasture. Aside from domestic animals, which may harmlessly snack on these insects, predators of all kinds usually have good years when cicadas emerge.

Cicada map 2021