Spiders measuring three inches across (about 8cm) have multiplied in the US state of Georgia, unnerving residents and prompting anxious posts on social media.

The Joro spider, native to east Asia, spins golden, wheel-shaped webs, some of them 10ft deep (three metres). Females have vivid yellow, blue and red markings on their bodies.

In the city of Winterville, Will Hudson estimates he has killed more than 300 of the eight-legged creatures.

Mr Hudson, an entomologist at the University of Georgia, said his front porch became unusable.

“The webs are a real mess,” he said. “Nobody wants to come out of the door in the morning, walk down the steps and get a face full of spider web.”

In Georgia, the first Joro was identified 80 miles northeast of Atlanta in 2014.

They have since been found in South Carolina, too, and Mr Hudson thinks they will spread across the southern US.

Common in Japan, China, Korea and Taiwan, Joros are not a threat to humans and will only bite if they are feeling threatened.

A researcher collecting them with her bare hands reported the occasional pinch, but said the spiders never broke her skin, Mr Hudson added.

It is not clear why there has been an increase in population this year, but it may be linked to the amount of rain.

“We see natural ebbs and flows in the populations of many different species that may be linked to local conditions, particularly slight changes in rainfall,” said Paula Cushing, an arachnologist at the Denver Museum of Nature and Science.

They are advantages to the Joros’ presence. Nancy Hinkle, another entomologist at the University of Georgia, said they help to suppress mosquitoes and biting flies.

They are also one of the few spiders that will catch and eat brown marmorated stink bugs, which are serious pests to many crops.

“This is wonderful. This is exciting. Spiders are our friends,” Ms Hinkle said.

“They are out there catching all the pests we don’t want around our home.”