You have just been introduced to the Trichonephlia clavata, more commonly known as the joro spider. Joro spiders are large, invasive orb weavers. The spiders were first seen in Georgia in 2013 and it is believed they were brought there on a shipping container from China.
Male and female joro spiders have different physical characteristics. Female spiders are hard to miss. They can grow to be inches long, have black legs, with yellow and silver stripes on their abdomen. Male spiders are small, and dull brown in color.
Emerging in the spring, the young spiders continue to grow until they reach full development in the fall. The spiders first seek a suitable location, and then mark their territory with golden wheels of woven silk that can stretch across several feet. They can be spotted in the forests, the countryside, cities, and living on the edge of roadsides and wooded areas.
Alan Harvey is a Professor at Georgia Southern University who studies field biology, evolutionary ecology, plant ecology and invasive species. As an expert in invasive species, Harvey believes that it is important to be observant of anything out of the ordinary. Researchers must also be careful when handling invasive species.
"We would generally prefer invasive species to sort of stay where they belong, not in their new invasive range, so you don't want to do things where you would accidentally be spreading it out to places where it wasn't before," Harvey said.
Dr. David R. Coyle is an assistant professor at Clemson State University, studying forest health and invasive species. Coyle and other scientists conducted an experiment in which they used iNaturalist and other datasets to predict the future growth of the invasive spider population.
The scientists first used the datasets to observe 20 factors in China, the native region of the spiders. They then marked those same factors in North America. The scientists used those markings to construct species distribution models. The computerized models are used to predict the spread of a species in different environments.
However, using datasets like iNaturalist can be tricky being that there are more datapoints in higher human populated areas. The accuracy of species distribution models are also put into question because they are based on predictions made by other scientists.
While the fuel behind the population growth of the spiders remains a mystery, the scientists noticed a difference in environments where they thrive.
“But we’ve been collecting some data, for the past couple of 3 years and we definitely see that where there’s a lot of joro spiders, you don’t have a lot of native spiders,” Coyle said. “So I think they it seems like they sort of crowd them out.”
University of Georgia Research Scientist Andrew Davis conducted an experiment in which he tested the response times of the spiders. For the experiment, they collected fully developed female joro and golden silk spiders. They also collected datasets detailing the startle responses of other species of spiders to compare to joro spiders.
Each spider was placed in a plastic container, where there were two puff of air blown on them with a turkey baster.
Reviewers did not believe the experiment was natural. While Davis agreed with this critique, he felt that it was better to conduct the experiment away from disturbances in nature.
From their observations, they found that joro spiders remained frozen longer than any of the other species of spiders. Their shyness is a response to potential disruptions in the environment. However, Davis believes that their shyness also may be essential in their survival in highly human populated areas.
According to Davis, joro spiders are spreading to the cool temperatures in the North, similar to those in their native region. While the spiders have established themselves in the South, they favor Northern temperatures. This will pose a problem in the future, as they will continue to spread throughout the United States.
Joro spiders are still a mystery to scientists. While spider personalities are still unknown, Davis believes that learning them will be the key to figuring out the future population growth of the spiders.
According to the Cleveland Clinic, "about 3% to 15% of the population has arachnophobia." The spiders can also be learning lessons on facing this fear. While their appearance may be intimidating, they exhibit timid behavior.
Just like any other species of spiders, joro spiders only bite humans when they are physically restricted and feel threatened.
When someone sees a spider on their property, their first instinct is to exterminate it. This process often involves the use of toxins. However, what they don’t realize is that those toxins will also harm other organisms that live there.
Instead of fearing the joro, Davis suggests naming it.
“And it’s harder to kill something that you’ve named,” Davis said.
Resources:
Arachnophobia (Fear of Spiders). Cleveland Clinic. 2021.