Formosan termites primarily cause damage through what activity?

Formosan termites are notorious for causing significant structural damage primarily because of their feeding habits, specifically through their consumption of cellulose materials. Cellulose is a primary component of wood, which includes not only trees but also many common construction materials such as paper, cardboard, and certain types of insulation. This feeding activity leads to the deterioration of the wood and can compromise the integrity of structures.

The other activities mentioned, such as digging tunnels and swarming, are related to their behavior but do not directly lead to the physical damage of structures. Digging tunnels is a means of foraging and creating nests but is secondary to the actual damage caused by their feeding. Swarming refers to the reproductive phase of their life cycle where young termites leave the colony to establish new colonies, and while it indicates population growth, it does not contribute to damage in the same way as their feeding does. Building mounds is also not a behavior associated with Formosan termites, as they typically create nests within wood or underground rather than building visible structures above ground.

Thus, understanding that the primary damaging activity of Formosan termites involves feeding on cellulose materials clarifies why this is the most pertinent aspect of their impact on structures.