The Joro spider: an eight-legged invader on the east coast

The invasion of the Joro spider raises questions about the balance of local ecosystems. As with other invasive insects, their long-term impact remains uncertain

The latest alarming eight-legged invader spreading along the East Coast of the United States is the Joro spider, or Trichonephila clavata. Native to East Asia, these spiders have spread worldwide and become common in the southern states of the USA. Experts now warn that they might soon “parachute” into northeastern states such as New York and New Jersey.

First sightings and spread

The Joro spider was first spotted in the United States in 2013, likely arriving via a shipping container traveling along Interstate 85 in Georgia. Since then, their populations have exploded, primarily in southern states like Florida, Georgia, and the Carolinas, but they have also been reported as far north as Ohio.

A 2022 study found that Joro spiders have a higher heart rate and metabolism compared to their relatives, the golden silk orb-weavers, which are confined to the South. This physiological trait allows Joro spiders to survive in northern states where temperatures drop below freezing (32°F).

Not Dangerous to Humans

Joro spiders weave golden, three-dimensional webs that can cover trees, houses, and power lines. Their bodies are marked with vivid yellow, red, and blue patterns, and their thin legs can extend up to the size of an adult’s palm. Although venomous, their fangs are not strong enough to pierce human skin. Additionally, they can use tiny silk parachutes to “fly.”

Potential arrival in New Jersey

The possibility of Joro spiders arriving in New Jersey by the end of the year has raised concerns among residents and local authorities. New Jersey Pest wrote on its website at the beginning of 2024:

“The potential for these spiders to establish populations in new regions raises questions about how local ecosystems will respond and adapt to their presence.”

However, there might be a silver lining to their arrival. One of their favorite meals is the brown marmorated stink bug, another invasive pest that has proven much more harmful to local ecosystems. Nonetheless, experts caution that it is still too early to determine if the Joro spider will ultimately replace native species.