Nuclear Polyhedrosis Virus (NPV) is a type of virus that primarily infects insects, particularly caterpillars. It belongs to the family of baculoviruses and is known for its ability to cause disease in various lepidopteran species. The virus is characterized by the formation of polyhedra, which are protein structures that contain the viral particles and help in their transmission. NPV is often used in biological pest control because it specifically targets pest insects without harming beneficial species. When ingested by the host, the virus replicates within the insect's cells, leading to its death. This makes NPV a valuable tool in sustainable agriculture, reducing the need for chemical pesticides.