Household pests include a variety of crawling insects, arachnids and rodents that enter the home to feed, nest or breed. Some of these pests are wood destroying insects or organisms that can damage the home. Some present a health hazard by spreading bacteria or allergens in our homes. Others may be a health hazard because they bite or sting. Still others are nothing more than a nuisance. The National Pest Control Association says the 10 most common household pests are cockroaches, mice, rats, termites, ants and carpenter ants, fleas, dog ticks, spiders, and silverfish.
The following contains general information on these and other pests:
Wood Destroying Insects (WDI) & Wood Destroying Organisms (WDO)
Wood destroying insects and organisms are a concern in any home with a wooden structure or components. Failure to properly identify and deal with the presence of WDI and WDO can lead to damage to the structure and other wooden components of the house and create the need for expensive repairs. The links below provide general information on the major varieties of WDI and WDO encountered in the United States.
Termites are social insects with a caste system that includes reproductives, workers and soldiers. Each caste has a unique role in the colony. The soldiers defend the colony against invaders (typically ants) and the reproductives yield new colonies. What makes termites a concern for humans is the worker caste, which bore through wood by digesting cellulose material from structural timbers.
A colony begins when the primary reproductives, also called the king and queen, mate and lay eggs. The eggs hatch into nymphs. The queen determines which caste the nymph will belong to based on the needs of the colony. She then secretes chemicals that transform the nymph into a soldier, worker or reproductive. The termite’s type/caste is determined by the secreted chemical.
While there are thousands of different termite species, there are three major species that are of economic significance in the United States…
- Subterranean Termites
- Formosan termites
- Drywood termites
- Subterranean Termite Treatment – Chemical Treatment
- Subterranean Termite Treatment – Baiting Systems
- Drywood Termites Treatment – Fumigation
Subterranean termites are the most common termite in the United States. A mature colony has from 60K to 300K workers. The average colony can consume a one foot length of 2×4 in 118 days. Subterranean termites can enter a home through a crack or void as small as 1/32″ in the slab or wall, any lumber in contact with the soil, an earth filled stoop, expansion joints, behind brick veneer, and through rigid foam insulation in contact with the soil.
Subterranean termites have three primary needs: food, which to the Subterranean termite is anything made of cellulose (i.e. wood, cardboard, books); a constant source of moisture, and shelter which is provided to the soil.
Subterranean termite workers are creamy white in appearance and the most plentiful caste in the colony. They forage for food to feed themselves and the rest of the colony. They create tunnels from mud (commonly called shelter tubes) to move above ground.
Subterranean termite reproductives, commonly called swarmers, are the winged members of the colony most commonly seen in the spring when they mate. The entire purpose of the swarmer is to create a new colony. Termite swarmers are often confused with a flying ant. Some common distinctions between the two are: ants have different size wings and few veins whereas a termite swarmer’s wings are identical with numerous veins. Ant antennae are elbowed, while termite swarmer antennae are straight. The midsection of the ant is pinched whereas the termite midsection is not.
Subterranean termite soldiers protect the colony against attack. They use their large heads to block holes in the colonies shelter tube and their strong mandibles to crush their enemies.
Formosan termites are sometimes called “super termites” due to their ability to cause significant damage in short periods of time. In fact, they are the most destructive wood destroying insect due to their large size and aggressive breeding habits. In fact, a Formosan termite colony can consist of 350 thousand to 2 million workers. Formosan termites are most commonly found in humid coastal and subtropical regions (i.e. Hawaii, South Carolina, Georgia, Florida and Louisiana).
Drywood termites feed and nest in wood which has a relatively low moisture content. Unlike Subterranean termites, they do not require any contact with the soil. These termites are usually found in the humid coastal and subtropical regions (i.e. California, Hawaii, Florida, Arizona, South and North Carolina, New Mexico, Texas, Alabama, Mississippi, Louisiana and Puerto Rico). They usually infest attic spaces or exterior wood members exposed to them when they swarm in early spring or summer. Typical evidence of drywood termites include damage, wings, pellets (fecal matter), and entrance/exit holes
Subterranean Termite Treatment – Chemical Treatment
A chemical treatment is the most common treatment type available for Subterranean termites.
The goal of a Subterranean termite chemical treatment is to establish a continuous termiticide barrier between the termite colony (usually in the soil) and wood in a building. This is done by placing termiticide in the soil on both sides of all foundation elements to provide a barrier preventing termites from entering the structure. Technicians trench the soil and inject termiticide beneath it at 16-inch intervals. They also drill into hollow masonry block foundations and inject termiticide into the block voids. This creates a protective barrier around the property, which is generally good for five years.
Subterranean Termite Treatment – Baiting Systems
In-Ground Baiting Systems are fast becoming a popular method of treatment for subterranean termites. A subterranean termite baiting system involves placement of cellulose (wood material) bait stations at strategic locations around the perimeter of the home. Worker termites – who constantly forage for wood to feed their colony – locate the cellulose bait stations and leave special scent trails to summon their mates to the food source. The cellulose material in the bait station is than replaced with a chemical inhibitor which retards the molting process in termites, preventing them from growing. The carrier termites then bring the chemical back to the colony and – if everything goes well – spread the inhibitor throughout the remainder of the colony. As a result of the growth inhibitor, the carrier and the rest of the colony will die.
Drywood Termites Treatment – Fumigation
If the inspector suspects that a Drywood termite infestation extends into concealed areas, they may suggest a tent fumigation. A fumigation involves placing the entire structure in gas-tight tarpaulin (which resembles a circus tent), releasing the gas inside the seal, and aerating the fumigant. Before fumigation can occur, the homeowner must removal all plants and animals, remove or place food items inside special protective bags, and stay out of the house for a three- day period. While the tent fumigation is more expensive and inconvenient for the homeowner, if done properly, it ensure the elimination all detected and undetected termites in the structure.
If the inspector suspects that the Drywood termite infestation is isolated to a local area, they may suggest using borates. This involves drilling small hole in which borates are injected or applied (using spray or foam applications) to the surface at the area of infestation.
Another local treatment involves wood injection. This method involves drilling holes into which termiticide is injected. This chemical will remain active in the wood after treatment to thwart resurging colonies.
If a Drywood termite infestation is isolated to a wood member which can be easily replaced or detached, the inspector may simply suggest wood replaced.
If there is any indication that there are galleries leading to adjacent wood members, treatment or removal of those wood members is required.
See our detailed carpenter bees guide.
See our detailed carpenter ants guide.
Powder Post Beetles
See our detailed powder post beetles guide.
Wood Destroying Fungus
Fungus (fungi, plural) is a plant that lacks chlorophyll. Unable to synthesize their own food, they feed off of cells in the wood. The fungi secrete enzymes that break down to wood (into usable food) and can significantly reduce the strength of the wood. It is estimated that Wood-Decay Fungi (found throughout the United States) causes as much, if not more, damage to homes as termites. While the average moisture content of wood is between 13-17 percent, fungus generally occurs when the wood moisture content exceeds 20 percent, coupled with mild temperatures.
Non-Decay Fungi. Sap-staining fungi leave wood with a bluish, bluish-black, gray or brown stain color. Surface-staining fungi (mold and mildew) leave the surface of the wood with a powdery or fuzzy appearance that varies in color. Though sap and surface-staining fungi do not significantly reduce the structural strength of wood, they are considered precursors to wood-decay fungi. White pocket rot produces small pits in wood and is only active in living trees.
Wood-Decay Fungi. White rot leaves wood with a bleached appearance and a spongy and stringy texture. Brown rot leaves wood with a dark brown, checkered appearance and a brittle texture. Note: wood that exhibits brown rot has lost its structural integrity and is easily crumbled. Water-conducing fungus or “dry rot” produces a decay similar to brown rot, but may vary in color.
Proper identification of the type of fungus is essential to developing the proper control measures. Surface-staining fungi can be cleaned with a 50/50 mixture of bleach and water, using a brush or power washer to remove the fungi from the surface of the wood.
For other fungi, the application of Borate wood preservative is a simple and effective control method. Borate is highly toxic to all wood destroying organisms and, unlike other wood preservatives, they are non-volatile, odorless, and are less toxic than table salt. They do not discolor the wood, are non-corrosive, environmentally safe and known to be effective in controlling more than 45 different species of wood decaying fungus. They are also effective in controlling beetles, termites, carpenter ants and a host of other insects.
If the fungi have actually damaged the wood, the corrective action will depend on the severity of the damage. The most effective and common method for moderate to severe damage is to replace the area of damaged wood. However, if only a small area is affected, borates and epoxies are a cost-effective alternative. The rotten wood is excavated and treated with borates. A liquid epoxy consolidant is then applied to harden the soft wood and, once cured, the epoxy wood filler is packed into the void. The surface can then be sanded flush and repainted.
Finally, all reasonable attempts should be made to remove the conditions that allow the growth of fungi, especially moisture. This may include installing a vapor barrier in the crawl spaces, sump pump and dehumidifier in the basement, providing proper drainage of rain and surface water away from the structure, removing sources of water penetration into the structure, and properly ventilating affected areas.