Termites and wood in a Costa Rica house
For owners · · 5 min read
Termites are part of the forest here. They recycle dead wood, and a house is, from their point of view, a large supply of it. Researchers who surveyed Costa Rica's termites named three as the main pests of buildings: a native tree-nesting species, an introduced subterranean one and an introduced drywood one. Each leaves a different sign.
Tree-nesting termites
This is the one everybody has seen: a dark brown, rounded nest on a trunk, a fence post or a roof beam, with thin brown tunnels running away from it. University of Florida entomologists describe the tunnels as about five millimetres wide or more, branching for thirty metres or further from the nest, along branches and up house walls. The colony eats dry and wet wood, hard and soft.
They swarm in the rainy season, usually after rain. Knocking the nest down rarely ends the problem, because a colony can have more than one nest. The same source says treating the tunnels and feeding sites with a non-repellent termiticide is effective, which is a job for a licensed pest control company.
Subterranean termites
These live in the soil and come up into a building for wood. Their sign is a mud tube about the width of a pencil climbing a foundation, a wall or a pipe, or emerging from a joint in a concrete slab. They need moisture, so leaks and damp ground beside the house help them.
Drywood termites
Drywood termites need no contact with the ground. A colony lives entirely inside one piece of wood: a door frame, a roof timber, a piece of furniture. The sign is a small pile of dry pellets, like coarse sand or coffee grounds, below a pinhole in the wood. Under a magnifying glass each pellet has six sides. They travel inside furniture, so second-hand pieces deserve a look before they come indoors.
What invites them
Wood touching soil. Timber, firewood or cardboard stored against a wall. Leaks that keep wood damp. Branches touching the roof. A concrete house is not exempt: the doors, frames, cabinets, ceilings and roof structure are often wood, and subterranean termites enter through joints and gaps in a slab.
Choosing and treating wood
Pressure-treated lumber resists termites and is the usual choice where wood is structural. Some tropical hardwoods resist them naturally, and the heartwood of mature teak is the best known. The pale outer sapwood of any tree does not, which is why two pieces sold under the same name can behave very differently. Borate treatments soak into bare wood and protect it for as long as it stays dry.
What to do on finding them
Identify which kind it is, because the treatment differs. Photograph the tunnels, pellets or damaged wood before cleaning anything away. A weekly look at the usual places catches an infestation while it is a repair to one door frame and not to a roof, and a yearly inspection by a pest control company is sensible for any house with a wooden roof structure.
Frequently asked questions
- What are the brown tunnels on my walls?
- Covered tunnels that termites build to travel between their nest and wood. Thin brown tunnels leading to a dark nest on a tree or beam belong to tree-nesting termites; pencil-width mud tubes from the ground belong to subterranean ones.
- What do drywood termite droppings look like?
- Small, dry, six-sided pellets that collect in a pile below a pinhole in the wood. They look like coarse sand or coffee grounds.
- Can a concrete house get termites?
- Yes. Doors, frames, cabinets, ceilings, furniture and roof timbers are all at risk, and subterranean termites can enter through joints and gaps in a concrete slab.
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