Few North American animals have been the source of more myths and misconceptions than the poorly understood Gila monster. Below is just a sampling of the most common fables. Most of this lore has its origin in less enlightened times, but many of it continues to be stated as fact by well-meaning individuals. In fact, I occasionally get emails from individuals stating that they enjoyed my web site, but feel obligated to correct some bit of information it contains. They then proceed to state one of these common myths. In spite of what you have heard, none of these contentions have any basis in fact.
A long-held belief has been that the breath of a Gila monster is nauseating and poisonous. Their diet of rotting flesh contributes to the fetid nature of their breath.
[The Gila monster]...emits its breath in a series of quick gasps. The breath is very fetid and its odor can be detected at some little distance from the lizard. It is supposed that this is one way in which the monster catches the insects and small animals which form a part of its food supply—the foul gas overcoming them.Scientific American, 1890
I once kept a cage of Gila Monsters for observation and study. I dissected and examined the teeth and other parts of the body under a magnifying glass. I found no venom except a gaseous form of poison, apparently produced by the eating of carrion. The poison gas is exhaled as a means of defense and is offensive and sickening."The Gila Monster," Arizona Times (Phoenix), March 12, 1949
Besides the Gila's suspected diet of carrion, their halitosis was often attributed to the accumulation of waste products due to the supposed lack of an anal opening.
Old settlers here know of many cases of Gila monster poisoning, in which the effect was death. I believe that the bite of the Gila monster is dangerous because of the creature's habit of eating lizards, bugs, and rodents, and then lying on the sand so hot that it blisters the hands and feet. The heat causes the food to putrefy in the stomach, evidenced by the fact that the teeth are often covered with a fermented, putrefied froth from the food. A bite has the same effect as the cut of a dissecting knife used on a cadaver, in other words, the inoculation of a deadly poison.Scientific American, 1907
It has been commonly held that if a Gila monster bites, it will not let go until sundown or until it thunders. Although these fables are false, Gilas do have a very powerful bite and are capable of hanging on tenaciously.
In spite of some old reports, there are no reliable accounts of human deaths from Gila monster bites.
It is called the "Heloderma" meaning the sunskinned reptile...a local naturalist...calls the Gila monster a hybrid, a production between a saurian and a snake...Its body resembles that of a lizard, while its head is that of a snake. It has a habit too, of throwing its tongue out like a snake and its bite is very poisonous and always fatal...Arizona Daily Star, Oct. 2, 1890