Exotic Joro spiders poised to spread across eastern U.S. states

An invasive species of spider spreading along the eastern coast of the United States can grow to the size of a human hand. Moreover, Joro spiders are capable of travelling long distances through the air.

Joro spiders, an invasive species from East Asia, will increasingly appear in New York, New Jersey, and other eastern U.S. states as summer approaches. The largest female Joro spiders measure up to 10 centimetres in length and have legs up to 20 centimetres—roughly the size of a human hand. Females are known for their bright yellow bodies, while males are usually smaller and brown.

As reported by "The Washington Post," Joro spiders have been in the United States for at least a decade. They first appeared in Georgia after likely arriving in the U.S. in a shipping container. A recent study conducted by David Coyle, a scientist working at Clemson University, showed that these arachnids will be able to "inhabit most of the eastern United States" this summer.

Unlike other large species, Joro spiders are adapted to the climate of the eastern coast of the USA, which is similar to that of Japan, where they primarily originate from. According to research conducted in February by the University of Georgia (UGA), Joro spiders also thrive in urban environments. "Flying" on their threads over busy roads, these invertebrates will continue to spread and inhabit cities.

Joro spiders are not dangerous to humans or pets. In fact, despite their "fearsome" appearance, these arachnids are shy and prefer to build their webs outdoors rather than in human homes. People who Joro spiders have bitten, a rare occurrence, have reported mild symptoms, according to a 2022 report by "The NY Post" from Richard Hoebeke, associate curator at the UGA arthropod collection. One reported bite caused swelling, a slight fever, and redness, possibly due to an allergic reaction.