Jorō spiders, also known as Trichonephila clavata, have been thriving in urban areas across the southeastern United States, according to a recent study published in Arthropoda. Unlike most creatures, Jorō spiders are not deterred by the noise and wind disturbance caused by busy roads. This unique ability allows them to inhabit urban areas that are typically avoided by native spiders. The study suggests that these spiders are well-suited to thrive and spread in similar locations throughout the country.
Lead study author Andy Davis, a research scientist at the University of Georgia’s Odum School of Ecology, explains that Jorō spiders can live next to roads despite the harsh conditions. He states, “If you ever look at a spiderweb next to a road, they’re jiggling and shaking, and it’s a cacophony of stimuli. … Roadsides are a really harsh place for an animal to live. But Jorōs seem to be able to live next to them.” Davis further adds, “It so happened to be the place where the spider got deposited about 10 years ago, and it just so happens that the (spider) that got dumped here is one that can do really well with humans.”
The Jorō spiders were first spotted in the United States around 2013 and have since rapidly spread across the southeastern states. These spiders are classified as orb weavers and catch prey using their giant, three-dimensional webs. The researchers conducted over 350 tests on spiders across 20 roads to determine how traffic noise affects their hunting abilities. Surprisingly, they found that spiders near moderate to heavy traffic roads were only slightly less likely to attack simulated prey compared to those near low-traffic roads. The study revealed that spiders near heavy traffic attacked 51% of the time, while those in less busy areas attacked 65% of the time.
Floyd Shockley, collections manager for the Department of Entomology at the Smithsonian National Museum of Natural History, comments on the spiders’ tolerance for urban environments. He states, “They’re capitalizing on easy hunting, easy access to prey. … They’re not particularly interested in us; they’re interested in the fact that we make the condition super easy for them to get the prey that they need to complete their life cycle.” Shockley also explains that Jorō spiders prefer making their webs on structures where lights are nearby, as the light tends to attract the insects they eat.
While past studies have shown that roads negatively impact insect abundance and diversity, Jorō spiders and other spiders within the Trichonephila genus are surprisingly urban tolerant. The researchers are still unsure why these spiders are better suited to city life than others. However, Davis plans to conduct future studies to investigate the physiology of Jorō spiders and their response to stress.
As the nonnative Jorō spiders continue to spread, they pose a threat to native species that are beneficial to the environment. However, at present, they do not appear to have a negative impact. Shockley warns that as their population increases, they could displace native spiders by consuming insects that are essential for the native spiders’ survival. During the study, evidence of Jorō spiders coexisting with native spiders was found.
It is important to note that Jorō spiders are venomous, but their fangs are incapable of breaking human skin. Therefore, they do not pose a direct threat to humans. Additionally, these spiders consume both beneficial and harmful species, including the notorious lantern fly.
In conclusion, Jorō spiders have proven to be highly adaptable to urban environments, thriving in areas where native spiders typically do not inhabit. Their ability to tolerate noise and disturbance from busy roads has allowed them to spread across the southeastern United States. While their presence may pose a threat to native species in the long run, for now, they can coexist with other spiders. Further research is needed to understand the physiological traits that make Jorō spiders uniquely suited to urban life.