Termites

What it is

Termites are social insects that live in colonies and feed on cellulose, the main material in wood and many plant products. In the Mid-Atlantic, the termite homeowners need to worry about is the eastern subterranean termite (Reticulitermes flavipes). Penn State Extension describes subterranean termites as the most economically important wood-destroying insect in the eastern United States. They are a hidden pest: the damage happens inside wood, out of sight, and can go unnoticed for years.

A colony with castes

A termite colony divides labor among castes:

• Workers are small, creamy-white and soft-bodied. They do the foraging, feeding and tunneling, and they are the ones doing the damage to wood.
• Soldiers have larger, darker heads and strong jaws, and they defend the colony.
• Reproductives include the king and queen, plus winged adults called swarmers (alates) that leave the colony to start new ones.

Why subterranean termites need soil

Eastern subterranean termites nest in the ground, where they find moisture, and travel to wood through soil and through enclosed tunnels. To cross open surfaces such as a foundation wall, they build pencil-width mud tubes. These tubes protect them from dry air and predators, and they are one of the most important signs to look for.

Life cycle

Termites go through egg, nymph and adult stages. A mature colony may produce swarmers once a year. The swarmers fly, shed their wings, pair up, and, if they land somewhere suitable with moisture and wood, start a new colony. Penn State notes that colonies can be large, with many thousands of workers, and that they can slowly grow over years.

How to recognize it

Swarmers

Swarmers are the most visible sign. In the Mid-Atlantic they typically appear in spring, often on warm days after rain. They are about a quarter to three-eighths of an inch long, dark brown to black, and have two pairs of wings of equal length, much longer than the body.

Finding swarmers inside the house, or piles of discarded wings on window sills, is a strong sign that a colony is nearby, possibly in the structure. Swarmers outdoors can come from a colony far away.

Termite or flying ant?

Winged ants and swarming termites are often confused. Check three features:

• Waist: termites have a thick, straight-sided waist. Ants have a narrow, pinched waist.
• Antennae: termite antennae are straight and beadlike. Ant antennae are bent, like an elbow.
• Wings: termites have four wings of equal length. Ants have forewings longer than hindwings.

Other signs

• Mud tubes on foundation walls, piers, or in crawl spaces.
• Hollow-sounding wood when tapped, or wood that gives way easily when probed.
• Blistered or sagging paint or drywall, and doors or windows that suddenly stick, can reflect moisture and hidden damage.
• Damaged wood with a maze of galleries that look layered along the grain and are packed with a mud-like material. Subterranean termites eat the soft springwood and leave the harder layers, giving the wood a layered look.
• Discarded wings near windows, doors and light fixtures.

Look-alikes

• Carpenter ants also damage wood, but they excavate smooth, clean galleries and push out sawdust-like debris. See the carpenter ants page.
• Powderpost and deathwatch beetles leave small round exit holes and fine powder.
• Wood rot can cause soft, crumbly wood without any insects.

Where you will find it

Outdoors

Subterranean termites live in the soil, often near wood-to-soil contact, mulch, firewood piles, tree stumps and old roots. They are drawn to damp areas, such as downspouts that discharge near the foundation or soil that stays wet.

Inside structures

Entry points are usually at or near the ground: slab cracks, expansion joints, gaps around pipes that penetrate the foundation, and wood in contact with the soil such as porch posts, door frames and steps. Termites can enter through gaps as narrow as a fraction of an inch. They are most common in crawl spaces, basements, sill plates and the framing close to the foundation.

Seasonality

Workers are active year-round in protected areas, but they are most visible in warm months. Swarms usually occur in spring. A swarm does not mean you have a problem in the house, but it is a reason to schedule an inspection.

Why it matters

Structural damage

Termites feed on structural wood, flooring, trim and even books and paper. Damage progresses slowly but continuously. Because they eat from the inside out, the surface can look fine until the damage is advanced. Repairs can be costly and, in serious cases, structural.

Often not covered by insurance

Standard homeowners policies commonly exclude termite damage, so a problem found late can fall on the homeowner. Check your own policy for what it says.

Real estate

Termite inspections are a routine part of buying and selling homes in many areas, and a past or active infestation can affect a sale.

Termites do not spread disease

Termites are not a direct health threat to people. Their impact is on property.

What to do

Look for signs, then call

You can do a simple, safe check:

• Walk the perimeter and look for mud tubes on the foundation, around pipes and at the sill plate.
• Check the crawl space or basement with a flashlight for tubes, damaged wood and moisture.
• Look for wings near windows and doors in spring.
• Take clear photos of anything suspicious.

Reduce what attracts them

Moisture and wood-to-soil contact are the main attractions, and these steps are safe homeowner maintenance:

• Direct water away from the foundation. Keep gutters clean and downspouts extended.
• Fix leaks, and keep crawl spaces dry and ventilated as advised by a professional.
• Keep firewood, lumber and mulch away from the foundation, and do not stack wood against the house.
• Keep soil from touching siding or wood trim, and remove old stumps and buried wood debris near the house.

These steps lower risk but do not remove an existing colony.

What not to do

• Do not rely on store-bought sprays or foams. They can kill the few termites you see while the colony continues unaffected below.
• Do not disturb tubes and damaged wood before the inspection.
• Do not rush to replace damaged wood until the termite activity has been treated, or the new wood can be attacked too.

When to call a professional

Termite control is a job for a licensed professional. Colonies are hidden, and correct diagnosis and treatment are specialized.

Call a professional if

• You see swarmers or wings inside your home.
• You find mud tubes, hollow-sounding wood or unexplained damage.
• You are buying or selling a house, or have never had an inspection.
• You see signs of past treatment or damage in a house you own.

A professional will inspect the structure and surrounding property, confirm the species, and explain the options. Ask about what is covered, how long the protection lasts, and what follow-up and re-inspection are included. Annual inspections are a common way to catch a new problem early.