MOBILE -- To the bafflement of insect experts, gigantic yellow jacket nests have started turning up in old barns, unoccupied houses, cars and underground cavities across the southern two-thirds of Alabama.
Specialists say it could be the result of a mild winter and drought conditions, or multiple queens forcing worker yellow jackets to enlarge their quarters so the queens will be in separate areas. But experts haven't determined exactly what's behind the surprisingly large nests.
Auburn University entomologists, who say they've never seen the nests so large, have been fielding calls about the huge nests from property owners from Dothan up to Sylacauga and over into west-central Alabama's Black Belt.
At one site in Barbour County, the nest was as large as a Volkswagen Beetle, said Andy McLean, an Orkin pesticide service manager in Dothan who helped remove it from an abandoned barn about a month ago.
"It was one of the largest ones we've seen," McLean said.
Attached to two walls and under the slab, the nest had to be removed in sections, McLean said.
Entomologist Dr. Charles Ray at the Alabama Cooperative Extension System in Auburn said he's aware of about 16 of what he described as "super-sized" nests in south Alabama.
Ray said he's seen 10 of them and cautioned people about going near them because of the yellow jacket's painful sting.
The largest nest Ray has inspected this year filled the interior of a weathered 1955 Chevrolet parked in a rural Elmore County barn. That nest was about the size of a tire in the rear floor seven weeks ago, but quickly spread to fill the entire vehicle, the property owner, Harry Coker, said. Four satellite nests around it have gotten into the eaves of the barn, about 300 yards from his home.
"I'm kind of afraid for the grandkids. I had to sneak down there at dark and get my tractor out of the barn," Coker said. "It's been a disruption."
Coker said he may wait until a winter freeze to try to remove the nest.
In previous years, a yellow jacket nest was no larger than a basketball, Ray said. It would contain about 3,000 workers and one queen. These gigantic nests may have as many as 100,000 workers and multiple queens.
Without a cold winter to kill them this year, the yellow jackets continued feeding in January and February -- and layering their nests made of paper, not wax. They typically are built in shallow underground cavities.
Yellow jackets, often confused with bees, may visit flowers for sugar, but unlike bees, yellow jackets are carnivorous, eating insects, carrion and picnic food, according to scientists.
"They were able to find food to colony through the winter," Ray said in a telephone interview.
He investigated a nest near Pineapple, measuring about 5 feet by 4 feet, that was coming out of the ground on a roadside. A southwest Pike County house in Goshen had a giant nest spreading into its roof.
Goshen Mayor G. Malon Johnson said he consulted Ray in removing it because he was concerned that children playing nearby could be attacked.
A colony has a maximum size in early July and August. The hot, dry conditions could force the yellow jackets out of ground nests.
"Normally it starts declining in the fall," Ray said.
He said the "super colonies" appear to have many queens.
"We're not really sure how this multiple queen thing works," Ray said. "It could be that the daughters of the original queen don't leave the nest or that the queens have developed some way to cooperate."
Ray examined a collected nest from Macon County to count the queens in it.
"We found 12 queens so far, so that's definitely a factor," Ray said Thursday.
Dr. Michael D. Goodisman, a biologist at Georgia Tech who has studied large nests in Australia, said he's heard of some large ones in Georgia and Florida, but not as big as those in Alabama.A 6-foot by 3-foot nest on a pond stump in Bulloch County, Ga., was featured July 12 on CNN.
"I'm not sure people know what triggers it," he said.
U.S. Department of Agriculture entomologist James H. Cane said he's familiar with a nest in Florida 10 or 15 years ago that engulfed a big easy chair. Cane said the monster nests reported in Alabama are intriguing and agreed with Ray that they could be the product of multiple queens in a single nest.
The nest usually dies out each year. "All that overwinters is the future queen," he said.
Given a queen's egg-laying rate, he said, there's no way a nest with a single queen could get that big in a growing season.
But in a multiple-queen colony, Cane said, there must be space where queens can't get at each other.