The Gila Monster

Heloderma suspectum

Gila Monster

A Gila monster searches for food in the Rincon Mountain Wilderness of Arizona. Photo by mlharing.

The Gila monster is a stout-bodied lizard that grows 18 to 24 inches in length. It has black, orange, pink or yellow broken blotches, bars and spots, with bands extending onto its blunt tail. Its face is black, and it has small, bead-like scales across its back. It is named for the Gila River Basin of the southwestern United States.

The Gila monster is one of only two species of venomous lizards; both are of the family Helodermatidae and both are similar in appearance and habits. Its venomous cousin, the Mexican beaded lizard (Heloderma horridum), is slightly larger and darker.

Most of the Gila monster's teeth have two grooves that conduct its venom, a nerve toxin, from glands in the lower jaw. The toxin is not injected like that of the snake, but flows into the wound as the lizard chews on its victim. While the bite can overpower predators and prey, it is rarely fatal to humans.

There are two subspecies of Gila monsters in the deserts of the Southwest:

  • H.s. suspectum (reticulate) resides primarily in the Sonoran and Chihuahuan deserts. Adults are mottled and blotched.
  • H.s. cinctum (banded) resides primarily in the Mojave Desert. Adults have a broad double crossband.


Mojave, Sonoran and Chihuahuan deserts of extreme southwestern Utah, southern Nevada, southeastern California, Arizona and southwestern New Mexico into Mexico.

Gila Monster Photo


Desert and semiarid regions of gravelly and sandy soils with shrubs. Found under rocks, in burrows of other animals and in holes it digs itself.


During warm weather the Gila monster feeds at night on small mammals, birds and eggs. Fat stored in the tail and abdomen during this period is utilized during the winter months. Both species of Heloderma are sluggish in habit, but they have a strong, tenacious bite.

Life Cycle

Gila monsters mate throughout the summer months, with the female laying 3 to 5 eggs in sandy soils, burrows or under rocks, during fall or winter.


Gila Monsters at Night


Desert Animal & Wildlife Index
Venomous Reptiles eBook



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