Thanks largely to milder winters and a plentiful food supply, yellow jacket wasps are now building "super nests" in Alabama, according to the Alabama Cooperative Extension System.
Entomologists believe that temperature increases in recent months have allowed these wasps to enter spring in larger numbers — around 15,000, to be exact — and, in turn, build perennial yellow jacket nests the size of a Volkswagen Beetle. In past years, colonies had numbered between 4,000 and 5,000 workers, forcing queen wasps to disperse and create multiple, much smaller nests.
"These perennial nests may be several feet wide and have many thousands of workers, far more than an average nest," Charles Ray, an entomologist who is currently working with the organization, said in a news release. "We have found them attached to home exteriors and other places you might not expect to find yellow jackets."
Researchers have already have found at least two abnormally large nests in Alabama and believe a third is in the works. Scientists had previously encountered 90 similar "super nests" in 2006.
"If we are seeing them a month sooner than we did in 2006, I am very concerned that there will be a large number of them in the state," Ray said. "The nests I have seen this year already have more than 10,000 workers and are expanding rapidly.”
In an average year, most yellow jacket wasps do not usually survive the winter, and those that do (oftentimes, the queens) build nests from scratch in the spring, Ray told NPR.
"The queens are the only ones who have [an] antifreeze-like compound in their blood so the queens can survive freezing," Ray explained.
By August, those new nests reach their peak volleyball size and are populated by thousands of males and queen wasps.
This year, however, Ray expects the number of perennial nests in Alabama to match the total from 2006. Homeowners who do come across a "super nest" on their property should keep their distance and contact a licensed pest control operator for help, he said.
"While these giant nests often appear less aggressive than smaller colonies, it is important that people do not disturb the nests," Ray said.