The GILA monster is a species of venomous lizard native to the southwestern United States and northwestern Mexico. It is the only venomous lizard native to the United States and is one of two species of the genus Heloderma. The GILA monster is a large lizard, growing up to 24 inches in length and weighing up to 5 pounds. It is characterized by its bright orange or yellow coloring and black markings. Its diet consists mainly of small mammals, birds, and eggs, as well as insects, amphibians, and other lizards.