Fumigation, fyoo muh GAY shuhn, is a method of killing pests that involves the use of toxic gases. It is widely used to eliminate weeds, nematodes (roundworms), and other pests from cropland. It is also used to protect such foods as grains and spices from rats and insects during storage. Goods shipped between countries often are fumigated to prevent pests and diseases from spreading from one country to another. Houses, apartments, and other buildings are sometimes fumigated to kill cockroaches, termites, and other insects.