Simplify the following text for a Grade 9 native English-speaking person.
Original: Termites mostly feed on dead plant material , generally in the form of wood , leaf litter , soil , or animal dung , and about 10 percent of the estimated 4,000 species ( about 2,600 taxonomically known ) are economically significant as pests that can cause serious structural damage to buildings , crops or plantation forests .
Simplified: There are an estimated 4,000 species ( about 2,600 taxonomically known ) . About 10 % are pests which can cause serious structural damage to buildings , crops or plantation forests .