Could the jorō spider really come to the Northeast US and Philly?

A recently published paper by a professor and student from Georgia has spun a web of stories that the invasive jorō spider, Trichonephila clavata, might soon be dangling from threads in the Northeast because it can survive cooler temperatures.

The paper in the Journal Physiological Entomology, written by researchers Andrew Davis and Benjamin Frick of the University of Georgia, demonstrated that 20 out of 27 jorō spiders tested were able to survive for several minutes in a lab at below freezing — indicating the spiders could expand north from their current habitats in the southeastern United States.

News reports of the spider have spread some breathless coverage, similar to the arrival of so-called murder bees, or Asian giant hornets, in the northwest in 2020.

The spider, native to Japan and eastern Asia, was first detected in Georgia in 2014. The jorō is thought to have been introduced and spread through the southeastern US through shipping containers and trucks. Because of its size and color, it is easily noticed and, therefore, easily tracked on popular apps such as iNaturalist by nonscientists as well.

In fact, there have been 2,031 sightings in Georgia detailed in iNaturalist. The spider has spread to North Carolina, South Carolina, Tennessee, and Oklahoma, according to the researchers.

The jorō, which, like most spiders, uses venom to paralyze prey, has not proved dangerous to humans. But it is notable because of its vibrant colors, three-inch length and another special trait: The orb weaver spins webs of three feet or more in diameter in trees or bushes, often within sight of homes.

Some news reports suggested the spider will soon permeate the Northeast. If they do arrive here, the researchers wrote, it will likely be through human transport, though they can travel locally, sometimes for miles, by stretching out a silk thread and catching a breeze.

Similarly, the spotted lanternfly, another invasive pest from Asia, has been able to spread rapidly by hitching rides on vehicles.

The researchers cautioned they have “no way of knowing if and how far the jorō spider range will expand,” though they noted the latitudes of the arachnid’s range in eastern Asia overlaps most of the latitudes in the US The paper only said the research “implies that it could spread northward beyond the southeastern USA.”

However Davis, one of the authors, said in one media interview that the spider might go as far as Delaware, which borders Pennsylvania.

Jon Gelhaus, a professor and curator of entomology at the Academy of Natural Sciences of Drexel University, said it was hard to draw any real conclusion from the study because the researchers tested the effect of a light frost only on adult spiders and not their eggs, which get laid through November. In other words, the eggs would have to survive much harsher, colder winter weather than is typically experienced in Georgia, as well as local parasites.

“I’m just not sure that from what they tested, you could really make a lot of pronouncements,” Gelhaus said. “The question is whether those egg masses can withstand the cold, and they didn’t have that information.”

However, Gelhaus said climate change and the continued warming of Philadelphia winters could alter future scenarios, possibly in urban settings because of the heat island effect — areas with few trees and lots of asphalt and concrete can be 20 degrees warmer than other areas.

» READ MORE: December 2021 was Philly’s second warmest on record. Climate change explains the trend.

If they do arrive locally, Gelhaus said, the big issue could be with other spiders and native species of insects, not humans, because they’ll be competing for space and food. They could overtake some local species because they might not be susceptible to local parasites.

Scientists such as Gelhaus take such threats seriously.

Sebastian Alejandro Echeverri, a Pittsburgh-based scientist who earned his PhD in ecology and evolution by studying jumping spiders, said that though he is not an expert on the jorō, he agreed the big impact would be on other spiders, not people.

“That could be a big deal ecologically,” Echeverri said in a Twitter message.

However, he doubts the jorō will have much of an overall impact in the region even if they do survive this far north.

» READ MORE: Philadelphia has a mysterious spider found nowhere else

“Will there be more of these spiders around on the East Coast?” he wrote. “Probably, about time?”

But he expects any impact, especially on humans, would be limited.

Echeverri noted that urban gardens in the Northeast already have species here of similar size, noting the Argiope aurantia, or the yellow garden spider, also known as the golden garden spider, and few seems particularly fazed by them.

“I’d say for the average person, they wouldn’t notice a difference between jorō spiders and Argiope.”

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