Wood Destroying Insects & Fungus

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:

• 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:

• 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).

Dry-wood termites:

• Dry-wood 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 dry-wood termites include damage, wings, pellets (fecal matter), and entrance/exit holes.

• 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.

• 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.

• If the inspector suspects that a Dry-wood 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 of all detected and undetected termites in the structure.
• If the inspector suspects that the Dry-wood 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 Dry-wood 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.

• The carpenter ant (Camponotus spp.) hollows out wood to create nests called galleries. Though they do not eat the wood, the boring activity can lead to structural damage in wood components. The by-product of the boring is called frass and looks similar to sawdust or pencil shavings. Frass is the most common evidence of carpenter ant infestation.
• Carpenter ants are similar in appearance to the common pavement ants, but can be distinguished by certain physical characteristics. The carpenter ant has a single pinched node between the abdomen and the thorax, while most ants have a dual node. In addition, the profile of the section from the abdomen to the head is almost perfectly rounded. Carpenter ants are especially common in the Northwest and the Pacific Northwest.

Treatment:

• The most thorough and effective way to treat a carpenter ant infestation is to locate the nest (colony) or nests and directly apply an appropriate pesticide. This may involve drilling into wood member and using pressure injection. It may also include drilling into the wall voids and on top of window sills and applying a dust-like pesticide. Another strategy involves laying out poison baits for the worker ants to take back to the nest(s). To prevent infestation, barrier treatments and removal of conducive conditions is recommended.

• The carpenter bee (Xylocopa spp.) hollows out wood to create nests called galleries. The carpenter bee does not live in the nest but stays in the nest to rear their young. The nest opening is a perfect half-inch circle. The nest itself may extend anywhere from four (4) inches (for a new nest with one bee) to 10 feet (for older nests with several bees). Carpenter bees generally nest in weathered or unpainted wood. They lay their eggs in the nest and seal them with a chewed wood pulp plug. The bees then emerge from the hole in the Spring.

Treatment:

• To properly eliminate a carpenter bee infestation, the proper chemicals or dust must be injected directly into the exit hole. The opening is then sealed by gluing a half-inch dowel into the opening and painting the surface. To prevent an infestation of carpenter bees, it is important to paint or stain any bare wood surfaces of Once the chemical or dust is introduced into the exit hole, the hole must be glued with a 1/2 inch dowel and painted over. To prevent an infestation of Carpenter bees, it is important to paint or stain a home’s bare wood surfaces.

• This term is used in the broad sense but it encompasses three closely-related families:
• The Lyctid or true powder post beetle.
• The Bostricid or false powder post beetle.
• The Anobiid or Deathwatch beetle.
• The beetle cycle begins when an adult lays an egg. The eggs hatch into larva. The larva eat the wood and digest it. The larva turns into pupa. Finally, the adult emerges to mate and the cycle repeats.
• Wood destroying beetles are usually transported in building materials, furniture and other wood products. The most common evidence of a powder post beetle infestation is a talcum powder-like substance know as frass. This frass falls from exit holes made by the beetles. An active infestation will reveal brilliant white frass (a color similar to that of sawdust from a freshly cut Christmas tree). Yellow to brown frass indicates an inactive or dormant infestation.

Treatment – Fumigation:

• If the inspector suspects that a powder post beetle infestation extends into concealed areas or is at numerous locations, they may suggest a tent fumigation.
• A fumigation involves placing the entire structure in gas-tight tarpalulin, releasing the gas inside the seal, and aerating the fumigant after. A fumigation for beetles is extremely costly since, unlike Drywood termite fumigations, ten times the amount of the fumigant must be used to ensure the beetle is eliminated.
• Before fumigation can occur, the homeowner must remove all plants and animals, remove or place food items inside special protective bags, and stay out of the house a three-day period. Again, while tent fumigations are more expensive and inconvenient for the homeowner, if done properly, they ensure the elimination all detected and undetected beetles.

Treatment – Borate:

• If the inspector suspects that the powder post beetle infestation is confined 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.

Treatment – Wood Injection:

• Another local treatment involves wood injection. This method involves drilling holes which an termiticide is injected. This chemical will remain active in the wood after treatment to thwart resurgent colonies.

Treatment – Wood Replacement:

• If a powder post beetle infestation is isolated to a wood member which can be easily replaced or detached, the inspector may simply suggest wood replacement.
• If there is any indication that there are galleries leading to adjacent wood members, treatment or removal of those wood members is required.

• 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.

Treatment:

• 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.

• 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.