Subterranean Termites, the most destructive species of termites are  found throughout the US and live in underground colonies or in secluded,  moist areas above ground.  Colonies can contain up to 2 million  termites and are comprised of three categories; Workers, Soldiers &  Reproductives.  Their distinctive tunneling (called mud tubes) allows  them to gain access to food sources and offer protection. 

Drywood Termites, their colonies are located in the wood they eat and  the colonies can have about 3000 termites. There can be several colonies  in one structure.  They destroy the wood by making galleries/chambers  in the wood.  Their fecal pellets are hard, elongated-oval, less the  1/25" in length with rounded ends and 6 concave sides.