Subterranean Termites

Subterranean termites nest in soil and build mud tubes to reach wood, causing more structural damage nationally than any other termite. They are uncommon but present in parts of western Washington, so recognizing the signs early matters.

How to identify subterranean termites

Small, pale, soft-bodied workers stay hidden; dark winged swarmers appear in spring. The hallmark is pencil-width mud tubes running from soil up foundations to wood.

Behavior & season on Whidbey & Fidalgo

They live in underground colonies and travel through mud tubes to protected wood, needing soil contact and moisture. Swarms typically occur in spring, which is often the first visible sign.

Why subterranean termites are a problem

They can cause extensive, costly structural damage while hidden, hollowing wood from the inside. Because they are less expected here, infestations can go unnoticed longer.

Signs of subterranean termites activity

• Pencil-width mud tubes on foundations or crawl-space walls
• Spring swarms of dark winged termites
• Wood that sounds hollow when tapped
• Discarded wings near windows and light sources

How Salty Dog treats subterranean termites

We assess the situation and treat active infestations, and address soil moisture and wood-to-ground contact that allow colonies to reach the structure. Learn more about our Wood-Destroying Pest Treatment service, or browse the full Pest Library.

Frequently asked questions

Are subterranean termites common on Whidbey Island?

They are far less common here than dampwood termites, but they do occur in the region — which is why the mud-tube sign is worth knowing.

What do the mud tubes mean?

They are protected highways from the soil colony to wood. Finding them means an active or recent infestation that should be evaluated promptly.

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