Termites spread slowly at first, then accelerate dramatically. A new colony produces fewer than 100 eggs in its first year, but serious structural damage to a home typically takes 3 to 8 years of ongoing feeding. The catch is that most infestations go undetected for years, so by the time you notice signs, termites have already been at work for a long time.
How Fast a Colony Grows
Termite colonies start small. Most subterranean species in the United States lay fewer than 100 eggs during their first year. Growth is gradual from there. A mature queen eventually produces 5,000 to 10,000 eggs per year, but it can take up to a decade before a colony is large enough to produce the winged swarmers that fly off to start new colonies.
By the time a colony reaches 5 or 6 years old, it may contain anywhere from several thousand to over a million termites, depending on the species. That’s a massive range, and it matters because colony size directly determines how quickly wood gets consumed. A colony of 10,000 termites and a colony of a million are doing very different levels of damage.
Species Makes a Big Difference
The three main types of termites in the U.S. spread at very different rates.
Subterranean termites are the most common. They live underground and build mud tubes to reach wood above the soil line. Their colonies grow steadily over years, and structural damage generally shows up in that 3 to 8 year window. They can forage across large areas of soil, with workers traveling well beyond the nest to find food sources.
Formosan subterranean termites are a more aggressive species found primarily along the Gulf Coast, in Hawaii, and in parts of the Southeast. Their colonies grow to at least four times the size of native subterranean termite colonies, and they consume wood at a significantly faster rate. Formosan termites also build their nests in unusual places: you may find mud tubes high up on walls, ceilings, or exterior fascia boards, and they construct “swarm castles,” odd-shaped formations of dried mud that sprout from walls or ceilings in late spring.
Drywood termites spread differently altogether. They don’t need soil contact and nest directly inside the wood they eat. Their colonies tend to be smaller, and the damage is more localized. They’re found mainly in coastal areas from Virginia south through Florida, along the Gulf Coast, near the Mexican border, and along the Pacific Coast up to just north of San Francisco. Because they live entirely inside wood, they can be carried long distances in furniture or lumber.
How Termites Reach New Structures
Termites spread to new locations in two main ways. Subterranean termites expand their foraging territory underground, building networks of tunnels through soil. When those tunnels reach your foundation, workers construct mud shelter tubes up the concrete or masonry to access the wood above. They can enter through cracks as small as 1/32 of an inch.
The second way is swarming. Once a colony is mature enough (typically after several years), it produces winged reproductives that fly out in large numbers, usually in spring. These swarmers pair off, shed their wings, and attempt to start new colonies nearby. Most swarmers don’t survive, but the ones that do establish entirely new infestations. If you’re seeing swarmers emerge from inside your walls, floors, or ceilings, that means a large, well-established colony is already feeding on your home.
Why Damage Seems to Appear Suddenly
One of the most frustrating things about termites is that the damage feels sudden even though it’s been building for years. Termites are almost impossible to detect early because they live hidden inside soil and wood, enter through concealed foundation cracks, and avoid exposing themselves to open air. Infestations rarely become obvious until the population has grown large enough to produce visible damage or swarmers.
This is why a homeowner might go from “no signs at all” to “sagging floor” in what feels like no time. The colony wasn’t new. It was quietly growing for years before anything showed on the surface. The 3 to 8 year window for serious structural damage assumes the colony started small in your home. If an existing mature colony reaches your structure from a neighboring property or nearby tree stump, the timeline compresses because the workforce is already large.
Conditions That Speed Things Up
Warmth and moisture are the two biggest accelerators. Termites consume and decay wood at much higher rates in warm, humid climates. This is one reason termite damage is more severe in the southern U.S. than in cooler northern states. Climate research suggests that as global temperatures rise, termite habitats could expand by more than 30% of their current range.
At the property level, the factors that speed up an infestation are practical ones: wood in direct contact with soil (deck posts, fence rails, siding that touches the ground), poor drainage that keeps soil moist near the foundation, mulch piled against the house, and clogged gutters that create moisture along exterior walls. Each of these shortens the distance termites need to travel and gives them the moisture they need to thrive.
Signs That Termites Are Already Spreading
Because early detection is so difficult, knowing what to look for can save you years of hidden damage. The clearest signs include:
- Mud shelter tubes on foundation walls, support piers, or plumbing under the house. These pencil-width tunnels made of soil and saliva are how subterranean termites travel between the ground and your wood.
- Swarmers or shed wings indoors, especially near windows, light fixtures, or emerging from walls. Large numbers mean a mature colony is present and has been feeding for years.
- BB-sized mud spots on interior walls or ceilings, sometimes called pinholes, where termites have briefly breached the surface.
- Sunken or wavy lines in paint, wallpaper, or drywall, caused by termites feeding just below the surface.
- Tiny six-sided pellets accumulating on floors or countertops, a sign specific to drywood termites pushing waste out of their tunnels.
- Structural problems like sagging floors, a bouncy feel underfoot, or door frames that crumble when touched.
Any of these signs means the infestation is not new. By the time damage is visible or swarmers appear, the colony has had years to establish itself. Acting quickly at this point limits further spread, but the early, invisible phase is already behind you.