Maryland, My Maryland

A Jorō Spider.

Watch out for the new Itsy Bitsy Spider. At the Balmer Sun, 4 things to know about the Jorō spider, which could reappear in Maryland this summer.

Jorō spiders were spotted in Maryland more than a dozen times last summer, the first major sighting in the area since the invasive species arrived in the U.S. from Asia in the early 2010s. And they could be coming back.

Scientists believe it’s possible the roughly 4-inch, yellow and blue arachnid reappears this summer. The spiders might look intimidating, but researchers say they pose no known threat to humans or pets. Here are five things to know about the Jorō spider.
 
Although the spiders originally came to Georgia from Asia, likely on international shipping cargo, according to a 2015 study from researchers at the University of Georgia, the species is known for its ability to travel well by air.

The Jorō can traverse ranges spanning at least 120,000 square kilometers, according to a 2023 study conducted by a group of researchers at multiple universities. They travel through the air along strands of silk, riding the current of the wind when they are babies and aim to locate a resource-rich home.

It’s in their nature to migrate away from areas scarce in food and toward regions flush with pests, said Michael Raupp a professor with the University of Maryland’s Department of Entomology.

“We’ve got lots of stinkbugs; we got spotted lantern flies, which [the Jorō spider] knew from Asia, where they evolved, so why not come to Maryland? Lots of good food up here,” Raupp said. “Heaven help us if they learn to eat blue crabs — only kidding.”

 Now, that would be impressive!

Jorō spiders primarily make their homes around buildings and on plants.

“These spiders are not going to come in people’s houses,” Raupp said.

The University of Georgia study found that the spiders mostly appeared in webs attached to the outsides of houses, near porch lights, on wooden decks and around shrubs and bushes near houses.

Although they are venomous, their fangs are believed to be too small to pierce skin, Raupp said, citing University of Georgia scientist Richard Hoebeke. Another report from Pennsylvania State University said the spiders are reluctant to bite, and if they do, the venom is weak and not medically significant.

This makes their primary impact as a consumer of pests in their massive webs.

“These are very timid spiders,” Raupp said. “They’re docile, and they’re highly beneficial.”

So, no, these are not the next great invasive threat, and in fact, they may help make a dent in some of the invasive insect species we've acquired. 

The look rather similar to the Yellow Garden Spider which is a fairly common species widespread in the US and nearly as big, around 3 inches max.  I suspect the Joro might prove to be stiff competition.