What to Know About Joro Spiders Expected to Invade the Northeast ...

7 Jun 2024
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Joro spiders - Figure 1
Photo The New York Times

Eight Legs and the Size of a Hand: All About the Joro Spider

Scientists expect the large, brightly colored spider to arrive in the Northeast sometime this year.

Joro spiders can be as large as eight inches long.Credit...Brynn Anderson/Associated Press

This summer might be a buggy one. As many as one trillion cicadas are emerging in the United States, spotted lanternflies are back and now scientists are predicting the arrival in the Northeast of a newcomer: the joro spider.

It’s unclear when exactly the joro, a large, brightly colored spider, will make its way to the Northeast. And there are some silver linings: There won’t be millions of them, and they eat other pests, including spotted lanternflies, which officials have urged New Yorkers to kill on sight.

Here’s what to know about these spider invaders.

How large are we talking about?

These spiders are big, about the size of a Post-it note or a stretched-out human hand, and have long legs, said José R. Ramírez-Garofalo, an ecologist at Rutgers University. The female spiders can grow up to eight inches long, while the males are roughly half that size, he said.

They can fly, sort of: They move through the air by shooting silk threads that catch the wind, and the air currents carry them along, although not very far. They also travel on cars and trucks.

The joro spider, which is a type of orb weaver, is native to East Asia. It was first spotted in the United States roughly a decade ago, in Georgia. The spiders have since spread to other states, including the Carolinas, Tennessee and West Virginia, according to iNaturalist, an online network of people sharing information about nature. The spiders have been seen as far north as Maryland so far, according to that database.

Where exactly are these spiders expected to go, and when?

Scientists estimate that the spiders will soon arrive in the Northeast, including New York and New Jersey. One scientific study last November found that the spiders were spreading faster to the North than the South, and were spreading to the Northeast the fastest.

But no one really knows when the spiders will arrive, said Mr. Ramírez-Garofalo, who is also the director of the Freshkills Biological Station in New York City.

“It could be as early as this year; it could really be any time,” he said. “All it takes is a couple to hitch a ride on a car, and they could establish, probably without any issue.”

The joro spiders found in Baltimore last fall were most likely transported accidentally by a vehicle, said Andy Davis, a research scientist at the University of Georgia.

“If it can happen in Baltimore, that means it can happen in New York,” he said, adding that he had even seen one of the spiders hanging off his car mirror while driving at highway speeds.

But why New York?

New York and nearby states are actually great habitats for these creatures. The Mid-Atlantic region is at roughly the same latitude as some of the countries in East Asia where the spiders are more widespread, so the climate is similar.

Mr. Davis said that based on their physiology and their temperament, “they will have no trouble adapting to the wilds of New York State or the wilds of New York City.”

Please, please don’t tell me they’ll be everywhere.

It is hard to say how many will arrive, but don’t expect trillions.

“Even if they do establish or if they are found in our area, chances are you’re only going to find a few of them, and they’re going to be highly localized,” Mr. Ramírez-Garofalo said. “It takes a long time for them to really spread.”

Do they bite?

If you leave these arachnids alone, they will leave you alone. If you are bitten by one of them, it will probably feel like a bee sting; their venom is mild and too weak to injure people.

The spiders are “exceptionally shy,” Mr. Davis said. “They’re not going to come get you.”

Should I kill them?

No. It is difficult to identify which orb weavers are the joro spider and which are garden-variety spiders that are native to the Northeast.

“They look so similar to our native species that I think your best bet is just not do anything about it,” Mr. Ramírez-Garofalo said. “Just leave them alone.”

Mr. Davis agreed, adding that from what he had seen in Georgia, the spiders had caused no “obvious damage” to the ecosystem.

“They’re definitely competing with our native spiders for food, that’s clear,” Mr. Davis said. “However, it also might be possible that the joro spiders could become food themselves for some of our native fauna.”



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