Joro spiders expected to eventually spread across most of the US: NPR

A large, brightly colored invasive species called the Joro spider is moving across the United States. Populations have been increasing in parts of the southern and eastern seaboard for years, and many researchers believe it is only a matter of time before they spread across much of the continental United States. United.

But spider experts say we shouldn’t worry too much about them.

“My feeling is that people like the weird, the fantastical and potentially dangerous,” said David Nelsen, a biology professor at Southern Adventist University who has studied the growing range of Joro spiders. “It’s one of those things that kind of checks all the boxes for public hysteria.”

Instead, scientists are concerned about the growing prevalence of invasive species that can harm our crops and trees – a problem made worse by global trade and climate change, which make local environmental conditions more comfortable for pests that do not previously could not survive freezing winters.

“I think it’s one of those ‘canary in the coal mine’ type species where it’s showy and gets a lot of attention,” said Hannah Burrack, professor and chair of the department of entomology at Michigan State University. But this shy creature poses little risk to humans. Instead, Burrack said, introduced pests like fruit flies and tree borers can cause more damage.

“This is a global concern because it makes everything we do in terms of conservation, agricultural production and human health more difficult to manage,” she said.

What is the Joro spider?

The Joro spider is part of a group of spiders called orb weavers, named for their wheel-shaped webs. They are native to East Asia, have a bright yellow and black coloring, and can reach up to 8 cm in length when their legs are fully extended.

However, they are quite difficult to spot at this time of year as they are still early in their life cycle, barely the size of a grain of rice. A trained eye can spot their softball-sized webs on a porch or their threads of golden silk covering the grass. Adults are most often seen in August and September.

Where are they going ?

Scientists are still trying to figure that out, said David Coyle, an assistant professor at Clemson University who worked with Nelsen on a study of Joro’s range, published last November. Their central population is primarily in Atlanta, but extends to the Carolinas and southeastern Tennessee. A satellite population has moved into Baltimore over the past two years, Coyle said.

As for when the species will become more widespread in the Northeast, a possible outcome suggested by their research? “Maybe this year, maybe a decade, we really don’t know,” he said. “They probably won’t get that far in a single year. It will take several incremental steps.”

Can they fly?

Babies can: Using a tactic called “ballooning,” young Joro spiders can use their webs to harness Earth’s winds and electromagnetic currents to travel relatively long distances. But you won’t see adult Joro spiders taking flight.

What are they eating?

Joro spiders eat anything in their web, which mostly ends up being insects. This could mean they will compete with native spiders for food, but it may not all be bad: a Joro’s daily catch could also feed native bird species, something Andy Davis , a research scientist at the University of Georgia, has personally documented.

As for some observers’ hope that Joro spiders could gobble up the invasive spotted lanternflies that are destroying trees on the East Coast? They might eat a few, but there’s “zero chance” they’ll make a dent in the population, Coyle said.

Are they dangerous for humans?

Joro spiders have venom like all spiders, but they are not deadly or even medically relevant to humans, Nelsen said. At worst, a Joro bite could itch or cause an allergic reaction. But these shy creatures tend to stay away from humans.

What could one day actually cause harm to humans is the widespread introduction of other creatures like the emerald ash borer or a fruit fly called spotted wing drosophila, which threaten the natural resources we depend on.

“I try to remain scientifically objective about this. And that’s a way to protect myself from perhaps the sadness of this situation. But there is so much ecological damage being done all over the world for many reasons, mainly because of humans,” Davis said. said. “To me, this is just another example of humanity’s influence on the environment.”