Inside the cell, the queen's body swells until it is large enough to hold many thousands of eggs. She can lay these eggs up to several thousand a day, and then the workers must carry the eggs to a special cell to take care of the larvae , or young, of the termites as they hatch from their eggs. Termites digest wood, paper, and any other material that contains cellulose, a substance that forms in the walls of plant cells, with the help of protozoa, microscopic one-celled animals in their bodies. These termites do much damage, especially in tropical rain forests where they occur in large numbers. One example is that railroad builders must specially import steel ties at great expense, because the termites would destroy all of the wooden ties.
Termites are also a problem in the United States.
Termites in the United States are classified into three groups, according to their habits. The subterranean termites , which are the smallest but most destructive, nest underground and live in wooden structures that extend for a considerable distance. The damp-wood termites live only in very moist wood, and cause trouble on the Pacific coast. The last group is the dry-wood termites , which need very little moisture and live in the Southwest. Only the subterranean termites have a true worker caste.