There are only two species of venomous lizards in the world, The Beaded Lizards (Heloderma horridum)  from Mexico and The Gila Monsters (Heloderma suspectum) which occur in the South Western USA.

The subject of countless superstitions and legends these large lizards (adults 18-20"), are still little understood as they spend 99% of their life underground.

They have been accused of being able to spray a deadly vapour into the faces of their enemies, of being able to leap two foot into the air, that once they have bitten a victim they will not release their bite until the sun sets, or it thunders, and many more such groundless superstitions. As is so often the case, the truth is just as (or more) interesting than the myth.

Gila Monsters are venomous, the poison glands being housed beneath the skin of the lower jaw, these glands have ducts that carry the venom to the mucous membranes located in a fold near the outer edge of their nine to ten semi-retractable lower teeth.

Unlike venomous snakes that inject their victims through hollow hypodermic like fangs, the Gila Monster envenomates its victims by chewing on them, the teeth have grooves flanked by sharp cutting edges that allow the venom to flow into the wound through capillary action. Besides causing severe pain the venom causes a rapid drop in blood pressure that can induce shock, although this will kill their prey effectively, they do not produce enough venom (17 mg  from an adult) to be a serious threat to man (32-70 mg would be required to kill a 150 lb person), and their venom does not contain the tissue damaging anticoagulants or digestive enzymes found in snake venoms. Though not life threatening to a healthy adult, the bite does still make you feel extremely ill , so I am told.

Despite the reputation of these creatures they are in fact the slowest moving lizard in the U.S.A (Max. top speed 0.5 MPH), they have good eyesight and acute hearing enabling them to avoid contact with man where possible, but if cornered they can show a remarkable turn of speed and agility in turning to face their enemy (humans being their main real threat). For such a clumsy looking lizard they are surprisingly adept climbers, competent swimmers, and reasonable diggers.

During the summer months Gila monsters have a preferred body temperature in the mid 80s F, and hibernate overwinter at approximately 50-60 F. Opportunistic feeders they will consume anything they can find, but because they are so slow this tends towards eggs of other reptiles and birds, carrion and the defenceless young of mammals.

Gila monsters eat their prey intact, this not only provides them with food but also supplies them with some of their water requirement, important in their desert habitats where water can be in short supply.

Gila Monsters lay between 3-12 eggs which in captivity take between 128-135 days to hatch, the offspring being totally independent miniature (5-6") versions of the adults from the moment they hatch. My own babies have hatched after 126-133 days at 6.5 inches with an average weight of 36.25 grams.
Notes by Jerry Cole