Why Do 17-Year Cicadas Appear Almost Every Year?

with a red orange hue and protruding red eyes. This coloring is an easy way to identify periodical cicadas from other species, including the more common dog day cicadas, which appear every year at the end of summer and have green tinged wings. Periodical cicadas make a rare appearance, relegated only to the regions east of the United States Great Plains, and nowhere else in the world. In eighteen nine, three observers began organizing periodical cicada as into broods. This makes

it easier to track the insects infrequent arrivals. Each brood includes different species of cicadas that emerge together in a collective and noisy bid to find suitable mates. There are twelve broods of seventeen year cicadas and three broods of thirteen year cicadas, which are more prevalent in the southeastern part of the United States. Each brood operates on a different schedule, which means you don't have to wait thirteen or seventeen years to witness the insects next in mass eruption.

After this year's brewed ten appearance, will get broods thirteen and nineteen four and brewed fourteen in. The sudden appearance of seventeen year cicadas is one of nature's most spectacular events, a phenomenon that perhaps led to the fanciful naming of the periodical cicadas genus classification magic Cicada. For centuries, periodical

cicadas have fascinated scientists and casual observers alike. Millions of cicadas may emerge in a single night after spending seventeen or thirteen years living underground, feeding off of nutrients sucked from the roots of trees and other plants. It's this lengthy childhood that serves as an important distinction that enables them to have the longest lifespan of any insect in North America, seventeen year. Cicadas spend the earliest months of

their final year burrowing towards the soil's surface. When the soil temperature rises above sixty four degrees fahrenheit or about eighteen degrees celsius, the cicada nymphs venture out of the soil. Their population may number a million or more in a space smaller than an acre less than half a hector, which helps survival rates. Animals ranging from spiders and birds to dogs and snakes find the lumbering cicada's easy prey, but will eat their fill long before they put a

dent in the population. The then flightless young cicada's journey upward at sunset, crawling a foot or more up any nearby vertical surface tree trunks, weeds, woody shrubs, homes, or outbuildings to begin the next phase of life. Overnight, they'll shed their nymphul skins a much like the fictional Incredible Hulk. The cicadas will split their shell like clothing to unleash larger bodies, and as they emerge through the tops of their shells, the cicadas will unfurl their wings for the

first time. Now the cicada is an adult, soft, ashen and vulnerable, waiting for its exoskeleton to harden and darken in color. It will leave its crunchy larval casing behind, still clinging to the cicada's first above ground resting place. The casing will be an empty and forgotten outline of the creature at once held. Not all cicadas appear on a strict schedule, though there are also some known as stragglers, that appear a year later or earlier than the rest

of their brood. One year early or one year late is the most common time frame for stragglers, but this isn't always the case either. In the year two thousand, for example, many brewd ten cicadas appeared four years earlier than expected. It Some observers theorize that unseasonably warm weather may cause some stragglers to emerge early. Others suggest delayed development may cause some stragglers to arrive late. Scientists aren't exactly sure how cicadas no seventeen years or thirteen years

have passed in the first place. They think it might have something to do with some property in the fluid that they suck out of tree roots for nourishment when they're underground, something that reflects the yearly cycle of the tree. Perhaps, if whatever this chemical signal is is weaker for insects under one type of tree versus another, that causes the off schedule appearances. Interestingly, the prime number appearances are thought

to help with survival. Since the cicadas are not on the same two year or five year cycle as most of their predators, the predators don't become dependent on them for food. Stragglers who missed the big party are more likely to be eaten off. Periodical cicadas, whether they're a thirteen year or seventeen year species, will live for just three or four weeks above ground, only long enough to mate and, in the case of female cicadas, deposit eggs. This mate then die cycle is pretty common in the

insect world. Male cicadas attempt to attract females with a loud buzzing that seems to undulate up and down between two distinct notes. Although each species of periodical cicada has its own song, the response of female cicadas varies little exactly one third of one second after the male's song ceases. A female responds with a click of her wings, but only if she wants him to make further advances. The male counters with the same call, hoping to hear another

wing click. If he does, he makes two particular sounds in quick succession, awaits for a third wing click, and then it's on. Within about ten days, the female will deposit some four hundred eggs in small twigs and branches of nearby trees and shrubs, but choosing from among the eighty or so species that they prefer to use as an nurseries. The females have protruding needle like devices at the end of their abdomens, which are used to create an egg cradle in the wood. Female cicadas may repeat

the egg laying process dozens of times. In about six weeks, white nymphs the size of ants will emerge from the eggs, drop to the ground and work their way into the soil. Like their parents, they'll spend the next thirteen or seventeen

years feeding on fluid found in plant roots. Although cicada's root feeding is considered harmless, damage caused by female cicadas burrowing into trees and shrubs to deposit eggs can be significant twigs may break off, which can create production issues for fruit and nut orchards, and some caretakers cover small trees with mesh cloth to prevent access to bark. Others apply in secticides before egg laying occurs, or simply opt

to wait out the cicada's limited lifespan. However, aside from this, these insects are generally harmless to plants and are harmless to people, so there's no need to panic if one lands on you. And what do you believe that cicada's make tasty high protein snacks? Apparently they taste like asparagus thanks to their plant based diets. The best ones to eat are those still in the nymph stage that don't have their hard outer shells yet. You can deep fry

them and serve them with spicy sauce. Today's episode is based on the article why do seventeen years cicadas come out more often than every seventeen years? On how Stuffworks dot Com? Written by Lori Elda. Brain Stuff is production of I heart Radio in partnership with how stuff works dot Com and is produced by Tyler Clay. For more podcasts my heart Radio, visit the i heart Radio app Apple podcasts, or wherever you listen to your favorite shows.