Spotted lanternflies are like this four years ago. The hottest new bug craze isn’t even the noisy crickets currently buzzing all over the Midwest. They are huge, yellow, ‘flying’ Joro spiders. Several articles would have you believe that there is a serious threat to humans from large numbers of spiders jumping out of nowhere straight into our faces. Although the size of these arachnids, especially the females, can be a bit scary and creepy, their threat to humans is quite low. Here’s what you need to know.
What are Joro Spiders?
Joro spiders (Trichonephila clavata) are a type of large orb weaver spiders. They are native to Southeast Asia, but were accidentally introduced to North America via a container ship.
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“They were first found in the United States in Georgia in 2014,” says Penn State University entomologist Michael Skvarla tells Popular science. “They have since spread across much of northern Georgia and adjacent parts of North and South Carolina.” They generally eat the small insects that get caught in their webs, including the invasive, voracious spotted lanternflies. These webs can be that too up to 10 feet wide.
These bugs are quite hard to miss. Adult females typically have a body about 1 inch (2.5 cm) long legs with a wingspan of up to four centimeters. The adult males are generally smaller and browner in color. “They are big and colorful. The only other web-building spider of comparable size in our area are golden silk orb weavers, which are native to the Southeast,” says Skvarla. “Golden silk orb weavers have a darker tan color, while Joro spiders are bright green and gray with black legs.”
Can they fly?
Although they can’t really fly, some studies show that this genus is particularly good at ‘ballooning’ or ‘parachuting’. Numerous arachnids can do this by shooting threads into the air that are still attached to their bodies. The wind then picks up the insects and carries them to another spot, creating the illusion that they are flying. They can move tens to hundreds of kilometers with this process.
Are they poisonous?
They are not toxic to humans and their teeth are not designed to pierce human skin. The poison they carry is weak and can only damage the smaller insects they eat.
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“The spiders are reluctant biters that prefer to stay in their web,” says Skvarla. “If bites happen because people deliberately handle Joro spiders, the venom is weak and bites are not even as painful as a bee sting.”
a 2023 study discovered that Joro spiders are among the most shy spider species in the world and prefer to just keep in place.
When will they arrive in the Northeast?
We don’t really know, but probably sometime this year. Joro spiders tolerate the cold and slowly crawl further north. A 2023 study found that they spread more quickly to the northern parts of the country than to the south, and spread most rapidly to the northeast.
How concerned should we be?
“Joro spiders are not a problem for humans, so the risk is overhyped. Their impact on the environment is unknown, but they appear to prefer urban areas, which are already highly developed and degraded,” says Skvarla. “My biggest concern is the impact they may have on native golden silk orb weavers, either through competition or hybridization.”
