How to deal with Subterranean Termites?

Subterranean termites live in the soil under your home and eat wood from the inside out. To deal with them, you need three things: early detection, professional soil treatment, and moisture control around your foundation. This guide covers all three, plus the warning signs, treatment costs in Los Angeles, and the prevention steps you take today.

What Are Subterranean Termites?

Subterranean termites are soil-dwelling insects. They build underground colonies and travel through mud tubes to reach the wood in your home. The species found in Los Angeles is the western subterranean termite (Reticulitermes hesperus).

These termites need moisture to survive. The soil gives them both moisture and protection. This is why they never live inside your walls the way drywood termites do. They return to the soil, then come back up to feed.

A mature colony holds 60,000 to 300,000 workers. Large colonies exceed one million members. Each colony splits into three groups:

• Workers. Cream colored, about 3 mm long. They do all the feeding and cause all the damage.
• Soldiers. Larger heads with dark mandibles. They defend the colony.
• Reproductives. Winged swarmers, dark brown to black, about 9 mm long including wings. They leave the colony to start new ones.

Subterranean termites eat more than structural wood. They damage books, leather, wallpaper, thatch, and even buried telephone cables. Anything with cellulose is food.

Why Subterranean Termites Are Hard to Detect

Subterranean termites stay hidden because they live underground and feed inside the wood. You never see the termites themselves. You see the evidence they leave behind.

Workers avoid light and open air. They build mud tubes, pencil-width tunnels made of soil and saliva, to travel between the soil and your home. They eat wood along the grain and leave a thin outer shell intact. A support beam looks fine on the outside while the inside is hollow.

Most homeowners find the damage during a remodel, a home sale inspection, or after a floor sags. By then, the colony has fed for years. The National Pest Management Association estimates termites cause $5 billion in property damage across the US every year, and subterranean species cause most of it.

6 Warning Signs of Subterranean Termites

Check your home for these signs twice a year:

1. Mud tubes on your foundation: Look along the stem wall, in the crawl space, and where plumbing enters the slab. Tubes measure about 6 mm wide, the width of a pencil.
2. Swarmers or discarded wings: Winged termites emerge in Los Angeles after the first fall rains, usually October through December. Piles of identical wings near windows and doors signal a nearby colony.
3. Hollow-sounding wood: Tap baseboards, door frames, and support beams with a screwdriver handle. Damaged wood sounds papery.
4. Blistered or sagging floors: Subterranean termites attack subfloors from below. Laminate and hardwood blister the same way water damage does.
5. Tight doors and windows: Termite damage warps frames. Doors stick without any weather change.
6. Mud in construction joints: Termites seal small gaps with soil. Check where the garage floor meets the wall and where porch steps meet the house.

Found one of these signs? Book a licensed termite inspection before you spend anything on treatment. An inspector confirms the species first. Treatment for drywood termites differs from subterranean treatment, and the wrong one wastes your money.

How Professionals Treat Subterranean Termites

Professional treatment targets the soil, not the wood. The goal is a treated zone between the colony underground and the structure above it. Three methods do this.

Liquid Soil Treatment (Termiticide Barrier)

This is the most common method. A technician applies liquid termiticide to the soil around and under your foundation. Modern products like fipronil (Termidor) are non-repellent. Termites pass through the treated soil without detecting it, pick up the active ingredient, and transfer it to the rest of the colony through grooming and feeding.

The process depends on your construction type:

• Trenching: The technician digs a narrow trench, about 15 cm wide and 15 cm deep, along the foundation and floods it with termiticide.
• Rodding: A soil rod injects termiticide deeper along the trench line, down to the footing.
• Vertical drilling: For slabs, patios, and attached garages, the technician drills holes through the concrete every 30 to 45 cm and injects termiticide underneath. The holes get patched after.

A properly applied liquid treatment protects your home for 5 to 10 years.

Baiting Systems

Bait stations go into the soil every 3 to 6 meters around your home’s perimeter. Each station holds cellulose bait laced with a slow-acting insect growth regulator. Workers feed on the bait, carry it back, and spread it through the colony. Over weeks to months, the colony collapses.

Baiting works well when trenching is not practical, such as homes with wells, cisterns, or drainage issues near the foundation. It requires ongoing monitoring visits.

Physical Barriers

Stainless steel mesh and sand barriers block termite entry points during construction or remodeling. These fit new builds and additions, not existing infestations. They contain no chemicals and last the life of the structure.

Read the full breakdown of our subterranean termite treatment options to see which method fits your property.

What Subterranean Termite Treatment Costs in Los Angeles

Expect these ranges for a typical LA single-family home:

Final price depends on linear footage, slab drilling requirements, and infestation severity. Get an exact written quote through a free inspection. Call (818) 940-0203.

Why DIY Treatment Fails Against Subterranean Termites

Store-bought sprays kill the termites you see. They never reach the colony. The colony sits 3 to 7 meters underground and holds hundreds of thousands of workers. Killing a few hundred at a mud tube changes nothing.

DIY attempts also make things worse in two ways. Repellent sprays push termites to find new entry points you have not treated. And disturbed mud tubes get abandoned, which hides the evidence a professional inspector needs to map the infestation.

Soil treatment requires licensed application. California regulates termiticide use, and correct dosage plus placement determines whether the barrier works at all.

9 Ways to Prevent Subterranean Termites

Moisture attracts subterranean termites. Remove the moisture and you remove the invitation. Do these nine things:

• Extend your downspouts: Direct roof water at least 1 meter away from the foundation.
• Clean your gutters: Overflowing gutters soak the soil right where termites want it wet.
• Remove standing water: Cover or drain anything holding water near the house, including plant saucers and clogged drains.
• Keep siding above soil grade: No brick veneer, foam insulation, or siding should touch or extend below the soil line. Maintain a visible 15 cm gap between soil and wood.
• Remove dead tree stumps: Stumps and buried roots feed colonies right next to your home. Grind them out.
• Break wood-to-ground contact: Deck posts, patio supports, and porch steps need concrete footings, never direct soil contact.
• Clear damp debris: Remove trash, leaf piles, and stored cardboard from around the foundation and crawl space.
• Fix every leak: Plumbing leaks, dripping hose bibs, and AC condensate lines keep foundation soil moist year-round. Repair them fast.
• Store firewood away from the house: Stack it at least 6 meters from the structure and raise it off the ground.

Building or remodeling? Ask about pre-construction termite prevention. Treating the soil before the slab pour costs a fraction of treating an infested home later.

Subterranean vs Drywood Termites

Los Angeles homes face both termites. The treatment differs completely so identification comes first.

Mud tubes mean subterranean. Small piles of pellets shaped like tiny grains mean drywood. An inspector confirms it either way.