The invader has a name: Magicicadas septendecim : small cicadas of three or four centimeters, black and orange. Of “17-year-old cicadas”, also called “zombie cicadas” because they spend their whole life underground in the form of nymphs, that is to say just before reaching adulthood. They feed on roots and sap before emerging from the ground to reproduce and die. Rest assured, this is a species that only exists in the United States. When they emerge from the ground, it becomes difficult to drive with the window open. Corpses litter the ground before disappearing, and males calling for females can make a deafening noise, up to 100 decibels, like a jackhammer.
The last large outbreak, near the federal capital Washington, dates from 2004. But, there were also in 2016 in states further south, such as Louisiana, where the species has a life cycle of more than 13 years. . For their counterparts further north, scientists at Virginia Tech University believe they are ready for their big breeding ball this year. But the outside temperature has to be around 17 ° C after a slightly humid night to see them all come out at the same time, which should happen within a few weeks. A slightly apocalyptic vision, which leaves you the urge to have a picnic.
Even if it is impressive, these cicadas do not sting, do not do like the locusts which ravage crops in West Africa by eating everything in their path. American arborists and winegrowers have still started to take precautions when covering their trees or plants.
The American scientists who study them do not really know why they live this way, but they believe that it is a strategy for the survival of the species. Thus, by all arriving at the same time for their reproduction, they delight their predators: birds, squirrels and other rodents. But faced with the quantity, nearly 2,000 insects per square meter, they cannot keep pace. And that allows a good part of the species to survive during the six weeks that they are reproducing. But this time capsule does not fully protect them, “zombie cicadas” are considered almost threatened in the United States, in particular due to of a mushroom but also because of the artificialization of soils. Difficult for them with the concrete to find their way out after 17 years of confinement underground.