Subterranean termites cause more damage to homes in the United States than storms and fires combined. Termites can enter your home through any wood that comes into contact with the soil, such as the exterior trim or cladding. A typical home may have three to four colonies under or around it. The three castes (workers, soldiers, and reproductives) have distinct functions. Swarmers develop from larger, wingless nymphs.
The male (king) and female (queen) will form a pair, lose their wings, and build a small cell in moist soil. Formosan termites are subterranean termites that live in the ground and build mud tubes and carton nests. Swarms appear on warm, rainy days at dusk and last into the evening. A typical colony consumes over 1,000 pounds of wood per year and is extremely aggressive. Formosan subterranean termites will chew through thin sheets of metal, mortar, PVC pipe, electric power lines, and telecommunications lines.
This termite will consume wood, paper, books, furniture, and other cellulosic materials. It is extremely difficult to detect in closed structures until severe damage has occurred. Moisture attracts termites and ants. Surface water must drain away from the building if the ground near the foundation is sloped or graded. Crawl spaces should have two square feet of ventilation openings for every 25 linear feet of foundation wall.
This helps to keep the ground dry and unappealing to termites. Trenching and treating or rodding to treat the soil on the outside of the foundation. Subslab chemical injections are typically performed by a professional pest control operator. Pressure-treated wood (chromated copper arsenate) protects against termites and fungi that cause wood decay.
With the advent of centrally heated homes, termites have become a threat in nearly every region and state in the United States. There may be as many as 13 to 14 subterranean termite colonies per acre on average, which means that a typical home may have three to four colonies under or around it. With as many as 1,000,000 subterranean termites per colony, the threat of infestation becomes very real.
Subterranean termites cause more damage to homes in the United States than storms and fires combined; colonies can have up to one million members.
Subterranean termites nest in soil to obtain moisture, but they also nest in wet wood. They will easily attack any wood that comes into contact with the ground. Termites can build mud tunnels or tubes to reach wood several feet above ground if the wood does not come into contact with the soil. They can also get into a structure via expansion joints in concrete slabs or where utilities enter the house.
Winged termites emerging from the ground near the house do not necessarily indicate that the house is infested, but it is a good reason to investigate further. Termites in the wood of houses or other structures usually come from colonies that have already established themselves in the soil.
Biology of Subterranean Termites
Termites are ant-like insects that are small in size. They differ from ants, however, in that they feed on the cellulose in wood. They can tunnel through wooden structural members in buildings and completely destroy them while working mostly unseen beneath the surface. A termite colony can enter your home through any wood that comes into contact with the soil, such as the exterior trim or cladding.
Termites are social insects that live in colonies with a caste system of labor. They have castes for reproductives and soldiers. There is a distinct worker caste in many termite societies, but the typical worker duties (nest building, food gathering, and feeding the reproductives and soldiers) are also handled by nymphs. Workers and nymphs do all of the work, while soldiers are only responsible for defending the colony.
Winged adults, also known as swarmers, are primary reproductives. During certain seasons of the year, they emerge from the colonies on colonizing flights. Following the flights, the male (king) and female (queen) will form a pair, lose their wings, and build a small cell in moist soil. They will mate, lay eggs, and raise the first workers. Secondary reproductives (without color or functional wings) are common in colonies where primary reproductives are absent.
The three castes (workers, soldiers, and reproductives) have distinct functions.
The life cycle of a termite
Biology of Subterranean Termites
Nymph \sNymphs
These young termites mature into workers, soldiers, or reproductives. As the nymphs grow in size, they begin to eat wood.
Soldiers
These termites guard the colony. They have mandibles, which are enlarged jaws that they use to defend the colony. They appear to be workers, but their heads are larger and darker in color than the workers'. They make up only 1 to 3% of the foraging termite population.
a subterranean worker
Workers
These are the termites that do the most damage by eating wood and tunneling, but they also keep the colony going, build and repair the nest, forage for food, and care for the young. Workers are the largest of the three castes.
reproductive winged
Reproductives
Reproductives come in the form of a queen, king, or alate. Primary and secondary reproductives are both possible. Primary reproductives have left other colonies. Secondary termites are found in mature colonies and serve as replacements if the primary reproductives are killed.
Winged reproductives (alates) are coal black to pale yellow-brown in color, flattened, and 1/4 to 3/8 inch long, with pale or smoke-gray to brown wings. Swarmers are another name for alates. During warm weather and rain, swarmers leave a mature colony. They depart from their mother colony to mate and establish new colonies. They become the new colonies' king and queen. Swarmers develop from larger, wingless nymphs. They have two pairs of equal-sized long, narrow wings.
After establishing their colony, the king and queen termites remain underground or within wood. They live for a long time, up to ten years, producing thousands of termites.
Subterranean Termites from Taiwan
Following WWII, these "supertermites" were introduced to the United States' coastal regions.
The winged reproductives of Formosan termites are pale yellow to brownish yellow, and the hairy wings have two dark veins at the leading edge.
The soldiers have a large oval head with toothless mandibles that cross at the tips. Formosan termites have been discovered in Gulf Coast states, along the eastern seaboard from Florida to North Carolina, as well as Tennessee, California, and Hawaii.
Formosan termites are subterranean termites that live in the ground and build mud tubes and carton nests made of soil and wood cemented together with saliva and feces.
Formosan termite carton nests retain moisture, allowing colonies and satellite colonies to establish aerial nests and survive without contact with the soil. Swarms appear on warm, rainy days at dusk and last into the evening. Formosan swarmers are frequently drawn to light.
Map of formosan termite-infested states
Subterranean Termite of Native Origin
Formosan termite colonies range in size from 100,000 to 1 million.
At least ten million. The largest known single Formosan termite colony was discovered in an Algiers, Louisiana public library building. Within a 600-pound nest, the colony contained over 70 million termites.
Aggressiveness
A typical colony will consume approximately 7 pounds of wood per year. Termite shields (when properly installed) can help control termites. The proportion of soldiers in a typical colony is less than 2%, making them vulnerable to outside predators such as ants. A typical colony consumes over 1,000 pounds of wood per year and is extremely aggressive. Termite barriers are ineffective. To reach wood or cellulosic material, Formosan subterranean termites will chew through thin sheets of metal, mortar, PVC pipe, electric power lines, and telecommunications lines. This termite will consume wood, paper, books, furniture, and other cellulosic materials. A typical colony has 10% to 20% soldiers, making it much less vulnerable to natural predators.
Adaptability
Moderately adaptable; more restricted range; species is ground-dependent for water, making detection via mud tubes easier. If they are present in the structure, they are usually concentrated on the first floor. It prefers damp dead wood. In most cases, it will not infest living trees. Extremely adaptable; does not require moisture from the ground; can survive on water condensation even at attic level. Creates carton nests in walls and roofs; the carton nest functions as a satellite home, trapping and conserving water. It is extremely difficult to detect in closed structures until severe damage has occurred. They also attack and cause severe damage to a wide variety of living trees; they prefer hardwoods such as oak, gum, and maple, but will also attack softwoods such as Southern Pine. Much more adaptable to different soil types, climates, and environments — from urban to wild.
Mobility
Moderate to low; dependent on the ground; and relatively weak flyers in the alate (flying stage) form.
Very mobile; moves around a lot when disturbed; not dependent on the ground. Ablates are proportionally more powerful flyers.
Formoson Subterranean Termites have devastated the state of Louisiana. Louisiana State University is a great place to learn more about these subterranean termites.
Subterranean Termite Prevention and Control
Mechanical Alternate: Avoid accumulating moisture near the foundation. Water should be diverted away from your home using properly functioning downspouts, gutters, and splash blocks. Surface water must drain away from the building if the ground near the foundation is sloped or graded. Moisture attracts termites and ants.
Proper ventilation will help to reduce humidity in crawl spaces. Crawl spaces should have two square feet of ventilation openings in the foundation for every 25 linear feet of foundation wall. Each exterior corner of the building must have one vent within five feet of it. This helps to keep the ground dry and unappealing to termites. Prevent shrubs, vines, and other vegetation from covering the vents. It is critical to have adequate cross-ventilation. To reduce excess moisture, cover 75 to 85 percent of the soil surface with polyethylene sheeting in crawl spaces.
There should be no contact between the woodwork of the building and the soil or fill. Exterior woodwork should be at least 6 inches above ground, and crawl space beams should be at least 18 inches above ground to allow for future inspections.
Sanitation
Never bury wood scraps or waste lumber in the backfill before or during construction, especially near the building. Remove any old form boards, grade stakes, or other items that were left in place after the building was built. Remove any old tree stumps and roots from around and beneath the structure. Never stack or store firewood lumber or other wood products against or within the crawl space. Keep trellises, vines, and other climbing plants away from the house. (Prevent any potential hidden paths of termite entry into the structure that could bypass any existing termiticide soil barrier.)
Treatments for Termites
Soil Treatments Termite treatments applied to the soil and adjacent to the building to form a continuous barrier.
Foundational treatments are the application of termiticide to a foundation in order to create a barrier against termites. The goal is to apply termiticide to all cracks in the footing as well as cracks in the foundation wall that may lead to the ground outside. Foundational treatment includes treating the inside of hollow concrete walls. Slab, basement, and crawl space foundations are the most common.
To form this chemical barrier, all three types of construction will require specialized treatment. Trenching and treating or rodding to treat the soil on the outside of the foundation, rodding beneath slabs, or vertical drilling and treating of outside slabs, stoops, or porches may be used for treatment outside the structure. Inside, treatments may include trenching and treating the soil along crawl space foundation walls, vertical drilling and treating slab foundations, rodding around bath traps and other utility openings, or directly treating wood.
Concrete Slab Construction: Although it is possible to trench around the outside of a poured slab, this usually does not provide satisfactory control because the termite colony may be entering the structure from the soil beneath the slab.
Chemical Treatments has more information on chemical treatments for subterranean termites.
After the slab foundation is completed, homeowners are not equipped to treat under slabs. Subslab chemical injections are typically performed by a professional pest control operator.
Borates (disodium octaborate tetrahydrate) such as Timbor or Boracare and/or pressure-treated wood (chromated copper arsenate) protect against termites and fungi that cause wood decay. However, termites can attack railroad ties, telephone poles, and pressure-treated wood over time. Mud tubes can be constructed on the surface, or entry can be gained through cut and cracked ends.
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