Scientists have been studying the invaders, which also sport bright red and dark blue hues, since they arrived in Georgia around 2013.

Within a few years, the huge webs of the Joro spiders became common in the forests of this region.

Woven at the height of humans, they can be more than a meter in diameter, and even serve them as a kind of parachute, to fly long distances thanks to air currents.

"The reason we started this project is because they literally fell into our laps," Andy Davis of the University of Georgia told AFP.

"They're pretty much everywhere here in North Georgia, they're all over my yard."

Probably arrived on board a container or a truck, they should now continue to colonize America, going north.

The researchers sought to track down their presence in the United States.

Specimens have been observed in South and North Carolina, Tennessee, and even as far as Oklahoma.

Without any help, these spiders would probably take about 20 years to reach the capital Washington, according to Mr. Davis.

Undated photo provided by the University of Georgia of a Joro spider, a species that is spreading on the east coast of the United States Jose ROMERO University of Georgia/AFP

But that will probably be the case much faster, he believes, because sometimes these little beasts find themselves inadvertently passengers of cars, and thus being transported over hundreds of kilometers.

The study by Andy Davis and his colleague Ben Frick also listed the specifics of these spiders.

They feed on small insects (midges...) and are able to survive brief periods of frost.

In general, being from Japan, they can adapt to temperate climates.

Call for clemency

Invasive species are often associated in people's minds with negative consequences.

This is for example the case of lycorma delicatula, an insect native to Southeast Asia landed in Pennsylvania in 2014, and known to decimate fruit trees and other plants.

But according to Andy Davis, Joro spiders don't have to be a cause for concern.

He compares them to another species landed in the United States 160 years ago from the tropics, the golden silk spiders (Trichonephila clavipes).

Undated photo provided by the University of Georgia of a Joro spider, a species that is spreading on the east coast of the United States Jose ROMERO University of Georgia/AFP

The latter are now present "everywhere in the South-East (of the country), and do not cause any damage", explains the researcher.

"They've been there for so long, they've integrated into the ecosystem, and the Joro spiders could be following the same trajectory."

They could even become the meal of certain predators, such as lizards or birds.

They are also not dangerous for humans, underlines Andy Davis, who calls for leniency.

"I really don't think Joro spiders deserve to be crushed or killed," he says.

"They really aren't after us, and it's not their fault they're here."

© 2022 AFP