Tuesday, October 19

The US awaits the hatching of billions of cicadas, the insect that emerges from the subsoil every 17 years | Ecology | Climate and Environment


Billions of periodic cicadas – a species of flying cicadas – prepare to surface, after completing their 17-year maturation cycle underground, with the objective of mating, for which they emit a deafening noise, comparable in decibels to which a powerful motorcycle produces, as a love claim. The phenomenon, which is scheduled to begin later this week, will be especially notable on the east coast of the United States, from Tennessee to New York.

The insects are part of a group called Brood X – also known as “the great brood of the East” – although only the males stridulate in search of a female. The chirp is the mating song, for which they flex a drum-like organ called a timpani. After 17 years underground, feeding and growing, the chorus of billions of cicadas chirping in unison will put a peculiar soundtrack to parks and gardens in the coming days.

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“An invasion is coming. This spring, billions of cicadas will emerge from the earth ”, warns the Twitter account of the National Mall, Washington’s vast compound of monuments and parks, which will be taken by storm by the noisy insects. The Environmental protection agency The US (EPA) has launched a campaign on social networks so that the population does not spray, since insecticides can affect living beings. Cicadas are harmless. They are a nutritious food source for other animals. Ignore them. They will not be here forever ”, assures the government agency. Periodic cicadas, which do not bite or attack humans, typically live for just over a month on the surface.

On their long maturation, and the accuracy with which they surface every 17 years, studies have shown that they can perceive time cycles because they are connected to the roots of trees, explains Daniel Gruner, associate professor of Entomology of the University of Maryland. Root fluid movement slows down in the winter and speeds up during the growing season. “However, we do not know how they keep track of the years one after another” until completing 17, continues Gruner, who points out that the timing is imperfect, since there are some that are ahead.

A group of cicadas last Thursday in the town of Chevy Chase, Maryland.
A group of cicadas last Thursday in the town of Chevy Chase, Maryland. ANDREW CABALLERO-REYNOLDS / AFP

The expert clarifies that the use of pesticides is not justified as a hypothetical remedy because cicadas “are not pests, they do not bite, they do not bite or transmit pathogens, nor do they damage crops or property.” Spraying, he adds, only increases health risks for humans and other animals. The entomologist at the University of Connecticut John Cooley argues that instead of waiting for their arrival in fear, their hatching is an opportunity to enlighten themselves: “We can learn more about our forests; understanding how they work is key to living in them sustainably ”.

Although they have not yet appeared en masse, it is not uncommon to find some exoskeletons already in the entrances of houses or to hear the click when they are crushed during a distracted walk through Washington. Two of the factors that make them emerge from the subsoil are humidity and warm temperatures, the ideal heat condition being a land at 18 degrees. “We have had a cold wave and that seems to have slowed down the process a lot,” says Cooley, who foresees that the final hatching should occur next week.

Cicadas spend most of their lives underground feeding on tree roots, before tunneling to the surface. Once outside, generally in green areas, they head en masse towards the trees. Females lay between 400 and 600 eggs on thin branches that they pierce with a series of punctures. Spiders and predators eat them, and according to the humans who have tasted them, they taste similar to tofu. There are several subspecies of periodic cicadas, with different life cycles and swarm volumes. The generation that is now emerging on the east coast, the Brood X, is the longest-lived and one of the mass hatching.

Entomologist Michael Raupp in front of a cicada at the University of Maryland.
Entomologist Michael Raupp in front of a cicada at the University of Maryland.CARLOS BARRIA / Reuters

The phenomenon usually lasts about 40 days. Considering that the buzz that a swarm of males emits to attract females can reach 90 decibels, the presence of these insects alters the daily life of citizens. The ear will be exposed to sounds as loud (and annoying) as those of a construction. According to Centers for Disease Control and Prevention (CDC), 50 minutes of exposure to the sound of a motorcycle can damage hearing. Many citizens decide to stay in their homes during this particular phenomenon, but this will be the first time it has occurred after 14 months of movement limitations due to the coronavirus, so it is unknown whether the desire to expand outdoors or the annoyance presence will be stronger. of the cicadas.

Within a month of being on the surface, they die. If the buzzes of the males take effect on the females, they will have succeeded in mating and laid huge amounts of eggs on the branches of the trees. In late summer or early fall, the newly hatching generation of Brood X will head underground to feed on tree roots. “We should enjoy this event for the amazing natural spectacle that it is, before they go underground for another 17 years,” says Gruner.

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