Palm-Sized Invasive Joro Spiders Are Much More Tolerant to City Life Than Thought, Could Have a Foothold Over US East Coast Cities, Scientists Warn

A new study has revealed that the invasive species of Joro spiders are more tolerant of urban life. This could potentially give them a foothold over urban areas and cities in the US East Coast.

Invasive Joro Spiders

In the past decade, invasive Joro spiders have spread through various states in the US. These species are orb-weaving spiders, which is a group known to produce webs that are circular and highly symmetrical.

Joro spiders can be easily recognized due to their unique yellow bands that cover their black legs. They also produce distinct webs that could span 1.8 meters across and have a golden reflection as they mirror sunlight.

Female Joro spiders can span up to 7.6 centimeters across, which makes them double the size of males. They also have red patches and blue stripes on their abdomens that are predominantly yellow.

After they mate during early autumn, female Joro spiders lay huge, web-bound clusters that contain up to 400 eggs. This is before they die off when winter starts, along with males. The eggs hatch during the spring. When this happens, the baby Joros make parachute-like webs that help them fly up to 160 kilometers away from where they were born.

Spread Across US

These creatures have been endemic to Asia. However, researchers were able to spot several Joro spiders across the US near Atlanta in 2014. Experts think that these invasive species may have been accidentally transported to the US through a shipping container.

Since then, these spiders have multiplied and spread quickly across the US thanks to their capacity for wide dispersal after birth. They can now be spotted in Georgia, North Carolina, South Carolina, and Tennessee. Other sightings have been reported in Oklahoma, Maryland, West Virginia, and Alabama. Experts think that they could spread through the US East Coast in the future.

Ever since they arrived, Joro spider webs have been observed to often be located near major roads. This came as a surprise, as the vibrations that are typically caused by busy roads could interfere with the hunting ability of these spiders. When smaller creatures end up trapped in spider webs, they struggle with breaking free. While this could alert the spiders to the presence of the critters, busy roads could end up drowning out the vibrations. In general, spiders are known to be extremely sensitive to vibrations.

Joro Spiders Thriving in Urban Areas

Now, in the new study entitled "How Urban-Tolerant Are They? Testing Prey-Capture Behavior of Introduced Jorō Spiders (Trichonephila clavata) Next to Busy Roads," researchers looked into how vibrations affect these spiders' hunting ability of simulated prey that were positioned on their webs.

In the lab, the team made use of tuning forks to simulate the vibrations that highways give off in order to see how they could affect the hunting ability of the arachnids. In 350 trials, vibrated spiders were observed to attack simulated prey 59% of the time, while non-vibrated Joros attacked the dummy prey in 65% of cases. The trials also revealed that roadside spiders could maintain a healthy body weight that is similar to that of other spiders. This shows that vibrations did not lead to long-term impacts.

Ecologist Andy Davis, the study's lead author from the University of Georgia, explains that the spider appears to have the capacity to make a living there, noting that the Joros were surprisingly urban tolerant.

While it remains unclear how these Joros could impact the ecosystems they invade, the findings posit that these arachnids are not leaving soon.

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