Why do subterranean termites not live entirely within wood?

Subterranean termites require a moist environment to survive, which is primarily why they do not live entirely within wood. Their bodies are adapted to high moisture conditions, and wood alone does not provide the necessary humidity. By nesting in the soil, they can maintain the moisture level they need for their survival and productivity. The moisture from the soil also supports their physiological processes, ensuring they stay hydrated and healthy.

In contrast, while other options may touch on aspects of their behavior or needs, they do not specifically capture the critical requirement for moisture that drives their nesting habits. For example, termites do not rely on moisture from the air alone, nor do they have the capability to find food in the soil in the same manner they do with wood. Additionally, although they do produce waste, this is more of an outcome of their feeding habits rather than a reason for their nesting behavior. The primary factor remains their need for constant moisture, which is why they establish their colonies in soil and not solely in wood.