A relatively invisible group of residents is sneaking into people's homes in Juneau, and the squatters are here to stay.
Homeowners and pest control specialists have found that carpenter ants have developed large colonies in wooden structures around town and caused severe damage.
"Carpenter ants are like tourists," said Fred Boehme, Southeast Alaska manager of Paratex Pied Piper pest control service. "If you see one or two in town, there are probably 2,000 more coming onshore."
Boehme has seen the most serious infestation in downtown buildings.
"Carpenter ants like moist, soft material. Most buildings in downtown are made of wood and are 80 to 100 years old," said Boehme, who has taken nine carpenter ant cases in August. He usually handles 40 to 50 carpenter ant cases a year.
"I will be happy if I don't have another carpenter ant job," Boehme said. "I charge some owners $800 at the most to clear the ants. But they might spend more than $40,000 repairing their houses."
Carpenter ants are among the largest species of ants in the United States. They have elbowed antennae, large heads and constrictions between the thorax and head and the thorax and abdomen. Winged females may be up to 18 millimeters long while males are about 11 millimeters long.
Edward Holsten, a research entomologist for the U.S. Forest Service, said although carpenter ants are a yearlong problem at homes, their existence is more obvious in June and July.
"This is when the ants grow wings and fly around to mate," Holsten said. "We get many phone calls in the summer because people are freaked out when they see these large ants in their houses."
Basin Road resident Ke Mell found out her house was infested with carpenter ants 10 days ago when she saw some winged ants on her wall. She called a local pest control company immediately.
Asked if she tried to kill the ants herself, Mell said, "Heavens no! I knew better. When I saw winged ants, I knew I had a big colony."
Her building contractor later told her that the ant colony in Mell's house is at least five years old. Mell's neighbor across the street found carpenter ants in her house, too.
Carpenter ants build their nests in wet wood. They attack the moist heartwood of living trees or hollow logs, house timber and soft wood that is wet. Occasionally, they tunnel into Styrofoam insulation.
"Unlike termites, carpenter ants don't eat the wood. They tunnel into wood for shelter and to raise the young," Boehme said. "The whole purpose of their life is to build a home, a nest."
Holsten said a young colony consists of only wingless ants. In the first year, the colony is small, made up of a queen, 10 to 20 workers and a few young. In succeeding years, colonies expand rapidly through winged ants and may have 2,000 individuals.
"The most obvious sign of infestation is the presence of ants inside the house," Holsten said. "Ants are active if they are nesting in heated places. Their presence can be detected by piles of sawdust-like material, or frass, from cracks made by ants."
Holsten said prevention is the best control.
"Building sites and adjacent areas should be cleared of stumps and partially decomposed logs," he said. "Lumber and debris in basements and crawl spaces are attractive to ants and may provide nesting sites."
People can apply boric acid powders around their houses, suggests Kathy Turner, pest scout for the Cooperative Extensive Service of the University of Alaska Fairbanks.
"It's like a barricade," Turner said. "The ants can still crawl through the powder but boric acid will scratch their waxy external body shell. The ants will dry up and die."
Holsten suggested people whose houses are already infested should find the ants' nest and spray pesticides.
"Carpenter ants generally cause minor economic loss. But if an infestation is longstanding, extensive repairs may be required," he said.
Mell doesn't know how much it will cost to repair the wood damage in her house. A wall of her basement and most of her deck were taken down.
"The ants and eggs just showered on the workers," Mell said. "But it's a job that needs to be done."
I-Chun Che can be reached at email@example.com.