Shortly after Donald Dickson built a home on the five acres he owns in Gainesville, Fla., he faced a problem all too familiar to him.
Within a year, termites invaded the wooden door leading to Dickson’s garage.
When that happened, in the early 2000s, Dickson said he knew he had to promptly handle the intrusion.
In his old apartment, he dealt with a termite infestation that ravaged a whole wall, which he ultimately had to replace.
“Man, we live in termite land, no doubt about that,” said Dickson, who recently retired from the University of Florida’s department of entomology and nematology. “If you lay a stick down on the ground in Florida, termites are going to be in it.”
So Dickson said he let university colleagues test an experimental termiticide on his property — a decision that saved him $3,000 in pest-control costs, he said.
For years, the chemicals guarded his house well. But this year, Dickson finished a barn that filled with termites quickly, despite the treated timber he used.
A common scourge that feasts on wood, termites belong to a group of pests — insects and mammals — that compromise the structural integrity of homes.
Most nonhuman species seldom raid our houses. A mere 5 percent of animals ever become pests, said Dawn Gouge, a public health entomologist at the University of Arizona. But those that encroach do so because we provide them with vital resources.
“Pests are typically invading our homes for three main reasons and they are pretty simple,” said Jim Fredericks, chief entomologist and vice president of technical and regulatory affairs for the National Pest Management Association (NPMA). “They’re looking for food, water or shelter.”
Regardless of the pest, do-it-yourself control treatments may be both ineffective and risky. While the industry works to create better and safer pesticides, some continue to carry environmental threats. If mismanaged, pest-control chemicals might pose health hazards. They also may target some infestations but not others — hence, the need for a professional inspection to properly identify and diagnose the problem.
But homeowners should know their abodes to a degree where seemingly negligible changes in the structure stand out. That awareness can help them detect furtive pest infestations, which many home insurance companies consider maintenance issues and do not cover.
Janet Hurley, an extension entomologist at Texas A&M University, said, “I tell everybody, having a home is like being the owner of your own Fort Knox because you’ve got to watch it and every little thing can lead to something else.”
Most pests are mere nuisances, but others are homewreckers.
Here are some of the most common unwelcome guests with the potency to damage our houses, the type of havoc they wreak and the methods to evict them:
Eastern subterranean termites occupy the entire United States, except Alaska. Drywood termites live in the South, while dampwood termites prefer the Pacific Coast and arid regions. Transplants from China, the particularly voracious and hard-to-control Formosan termites are found in several southern states and Hawaii.
Termites are tiny bugs with beady bodies and large heads, decorated with prominent mandibles, or jaws.
With the digestive help of bacteria in their gut, termites devour wood to extract cellulose and other nutrients. In the wild, they are recyclers.
“Of course, when they’re trying to recycle the wood in your home, then that generates a lot of anxiety for people,” Gouge said.
The NPMA estimates that termites cause $5 billion worth of property damage every year.
The severity of destruction depends on the kind of termites and the size of their colony, among other factors. But Orkin, a pest control company, states that in about five months a 60,000-strong termite community can munch through a foot-long, 2-inch-by-4-inch beam. That is roughly equivalent to an average loaf of bread.
“They can do a ton of damage and it often depends on the foundation style of the house,” said Bernard Buttone, chief operating officer at Triangle Pest Control in the Carolinas and Colorado.
For instance, crawl spaces, or one- to three-foot-high gaps that practically replace basements in humid areas prone to frequent showers, can trap moisture and, thus, spur the decay of any exposed wood. That attracts termites.
Concrete slab foundations may serve as a break between structural timber and the soil, where commonplace eastern subterranean termites live. But if an infestation does occur, that type of a base complicates inspections and some kinds of treatments.
Still, John Kane, a Midwest division entomologist with Orkin, said, “There’s a famous saying about termites that there are two kinds of houses — those that have termites and those that will have termites.”
This holds true even for homes in northern states, where termite activity is somewhat sluggish because of cold weather but equally likely to produce substantial damages if left unimpeded.
Signs of invasion
Subterranean termites construct “mud tubes” that help them travel to structures from underground. Seeing these mucky veins — which can vary in scale from a pencil to a finger — on the exterior of a house is a sure sign termites are in the structure.
Paint blisters on walls are another indicator of termites’ wood-eating operation. These bubbles form because most termites need to keep “97 and a half percent humidity,” in their colonies, said Phil Nixon, retired extension entomologist at the University of Illinois.
But what is perhaps the most definitive evidence of termites are termites themselves. While generally cryptic, winged termites swarm outside of the colony to mate in spring. After that ritual is over, they clip their wings and retreat back.
Spotting individual termites (which could be mistaken for winged ants) or truncated wing pieces (which often get trapped in spider webs) “would be a good indicator that there’s been a termite colony present for a couple of years at that time,” said Matt Frye, extension entomologist at Cornell University.
What to do about them
Treatment methods differ in how they attract and impact termites.
A network of bait stations, for example, lures the soil-borne subterranean termites through a mixture of cellulose and insecticide, which they subsequently bring to the colony.
What Dauphin Ewart, president of Texas-based pest control company Bug Master, uses are cartridges placed 10 inches deep into the soil every 10 feet around a home. While the bait material needs to be occasionally replaced, the system can hold for 20 years, Ewart said.
A bait system “allows you to see over time whether you in fact have termite activity in the ground,” he said.
Soil treatment is another option, which normally consists of digging up a trench around a house and injecting termiticide into the soil.
“I personally prefer [this option] because you come in and treat the house once and you’re done,” said Ron Nelson, owner of Wyoming Termite & Pest Control, adding that bait stations are inexpedient in cold climates, where the soil freezes for months on end.
The chemicals used could either function as a barrier that repels the bugs, keeping them away from a home, or as a poison-laced loop that attracts them, annihilating an indoor colony.
That “trench-and-treat” method, however, offers no instant means to gauge its effectiveness, which could deflate if the soil is disturbed.
For drywood termites, which do not live underground, whole-house fumigation and topical pesticides are two common treatment approaches, said David Minder, service manager at Pinnacle Pest Control in California.
Costs: Ranging from a few hundred dollars to several thousand dollars, depending on method used, property size, type of termites and severity of infestation.
They are found in the northeastern and northwestern United States.
As their name suggests, carpenter ants — which can reach nearly an inch in size — burrow in wood. Unlike termites, they do not eat timber; they dig tunnels and galleries in it for shelter.
“Fortunately, the damage is somewhat small compared to what termites can do,” said Jeffrey Hahn, extension entomologist at the University of Minnesota. “You can have carpenter ants for a few years and not have any appreciable damage. But, of course, the larger the nest, the longer they are in the home, the more likely it is they could cause some sort of more significant damage.”
Large carpenter-ant communities may include 50,000 individuals, according to the NPMA. In search of resources, the main colony, which often lodges in trees, may spawn a satellite one in nearby houses.
“The nest is typically the size of a two-foot, 2-inch-by-4-inch [plank],” said Nixon, the retired University of Illinois entomologist, “and a human-occupied house is unlikely to have more than one nest.”
While damp wood entices carpenter ants, they also burrow in sound timber, said Rebecca Maguire, extension coordinator and entomologist at Washington State University. Sometimes, however, they would occupy wood bored out by termites, creating little further damage.
Signs of an invasion
“Because they’re forming nests in the wood and not eating the wood, carpenter ants need to leave the nest to find food,” said Michael Skvarla, extension entomologist at Pennsylvania State University.
In the open, worker ants scurry along natural “highways” such as wires, pipes and cracks.
Earlier this year, Skvarla spotted carpenter ants in his own home in State College, Penn. “We were seeing 10 or 20 ants in the house a day,” he said. “Just crawling here, crawling there, crawling everywhere, up the walls and on the floor.”
When the critters hide in their nests, fine sawdust — from the wood they excavate — and tiny surface holes give away their tenancy in a home.
How to treat them: Skvarla used Termidor, a popular pesticide.
Dousing the interior and exterior of a home with insecticide is a standard and effective way to halt the intrusion of carpenter ants.
“It attaches to them and they take it back to the nest and eliminate it,” said David Isenberger, sales manager at Idaho-based Pointe Pest Control, of the pesticide the company uses.
“It is very low evasive,” he said.
Cost: a couple hundred dollars.
House mice, deer mice and Norway rats are found throughout the United States; roof rats are found in the coastal and southern United States.
Attracted by the availability of food and the room temperature in our homes, all sorts of rodents come in. Mice and rats, however, are the most likely visitors, carrying diseases and inflicting damage.
A mouse can squeeze through a hole the “size of a nickel,” said Buttone of Triangle Pest Control. Rats are also quite adept at forging their way inside residences.
“I’ve seen Norway rats get through sheet metal; I’ve seen them get through concrete,” said Thomas Miche, president of Miche Pest Control in Virginia. “They usually don’t go straight through concrete, but they’ll take something that’s already been cracked or damaged and they’ll just make the hole bigger.”
Once inside, mice and rats incessantly gnaw on various surfaces to trim their constantly growing teeth. “They are associated with chewing on electrical wires, which is a really frustrating thing to happen for a homeowner,” Bug Master’s Ewart said.
Wires bared out by rodents can ignite. The NPMA reports that, by mangling cords, rodents probably spark some 25 percent of fires with unknown causes.
Signs of an invasion
While seeing a mouse or a rat scurry across the floor is possible, what usually betray them are their droppings. Because rodents hastily reproduce, a growing infestation leads to a rising amount of excrements.
With roof rats, which take up residence in attics, “if there are lots of them, they can have urine that sucks through the insulation and into the ceiling,” said Rebecca Baldwin, entomologist at the University of Florida.
How to treat them
“You have a lot of different options,” for mice, said Nelson of Wyoming Termite & Pest Control, including rodenticide, traps and even glue boards to which the creatures stick, unable to move.
Averse to journeying far from their nests but quite curious of their immediate surroundings, mice are easier to catch than rats are.
Travelers by nature, rats are smart and timid, wary of new objects, Miche said. Thus, any approach to handle a rat infestation may require multiple visits from pest experts, which leads to higher costs.
Additionally, expenses hinge on the form of rodent control, which also may impact a house’s habitability. Some traps, for instance, could harm children and pets, while bait stations might result in fetid odor from dead rodents that often need to be fetched out of their nests.
Cost: a few hundred dollars, depending on the type of control and severity of infestation.