Thirteen venomous animals of the Southwestern desert. Which is the most dangerous?

Deserts of the southwest have a reputation for venomous critters. Do you know which is the most dangerous? It’s not the one in the picture.

I attended a lecture at the Arizona-Sonora Desert Museum  given by James W. Cornett, a biologist, author, and emeritus Curator of Natural Science at the Palm Springs Desert Museum. Cornett has studied venomous animals for over 30 years and gave us a list of what he considers the thirteen most dangerous animals.

This list is subjective and includes consideration of the toxicity of the venom, the amount of venom injected, the possibility of an allergic reaction, the abundance of the animal, and the probability you could actually encounter the animal. Here is his list from the least dangerous to most dangerous (the links take you to the Arizona-Sonora Desert Museum digital library for photos of the animals):

13. Tarantulas.  The venom is generally not dangerous to humans and it takes much provocation to get a tarantula to bite you. I handle tarantulas at the Arizona-Sonora Desert Museum and haven’t been bitten yet.

12. Centipedes. Some of these can get over 20 inches long (but most are about 5 inches) They deliver venom by pinching with its front legs. One death has been attributed to a centipede bite.

11. Velvet ants (actually wasps). These look fuzzy and cute but deliver a very painful bite.

10. Gila monster.  These lizards are venomous but it takes much provocation to get them to bite you. The neurotoxic venom causes intense pain, edema, bleeding, nausea and vomiting. A friend of mine recently was bitten by a Gila monster and he can attest to the intense pain. While he was in intensive care at the hospital his blood pressure dropped to 36/10 at one point. There is no antitoxin. He did survive, with no apparent aftereffects.

9. Coral snakes. The coral snakes in the Southwest are generally small. Venom is neurotoxic like that of a cobra but it posses less danger than a rattlesnake because coral snakes here are small and have small fangs. More deaths occur in the East where the snakes are larger.

8. Cone-nosed bugs (aka Kissing bugs). Bites from these bugs can produce an allergic reaction and can transmit Chagas Disease, a chronic and debilitating protozoan infection. Cone-nosed bugs feed on the blood of other animals, mostly rodents.

7. Ants.  Swarming ants, by their large numbers can deliver painful bites and cause allergic reactions.

6. Scorpions. Most scorpion stings in the southwest are not dangerous. However, bark scorpion venom is dangerous to humans.

5. Brown spiders. The venom is very persistent and causes tissue damage.

4. Wasps. The pepsis wasp  (aka tarantula hawk) has the most painful sting of any insect.

3. Black Widow spiders. Drop for drop, black widow venom is the most toxic of any animal in the southwest. And now, we are seeing more Brown Widow spiders coming into the area.

2. Rattlesnakes. This venom does great tissue damage and two species, the Tiger rattlesnake and Mohave rattlesnake, also have neurotoxic venom. By the way, there are 18 rattlesnake species common to Arizona.

And the most dangerous venomous animal:

1. Africanized Honey Bees.  According to Cornett, bees cause more deaths than all the other animals combined. There are about 1,100 species of bees in Arizona; most are harmless.

Besides these animals, Cornett mentioned some snakes that are considered only mildly venomous, some of which are commonly kept as pets. None of these snakes have fangs, but the do have enlarged back teeth and toxic saliva. They need to chew on you for a while to work the venom in. These snakes include the ring-necked snake, black-headed snake, spotted night snake, lyre snake, hog-nosed snake, and the common garter snake.

Cornett related an incident with a hog-nosed snake. This snake was in an exhibit at the Palm Springs Desert Museum. Cornett was attempting to feed it a mouse, but since he handled the mouse, its scent got on Cornett’s hand. The snake bit him on the web between thumb and forefinger and chewed for a while before it could be detached. This mild venom caused swelling and discoloration of Cornett’s hand and arm and produced blisters for about a month. Nobody has antivenom for these snakes.

Be careful out there.

Copyrighted by Jonathan DuHamel. Reprint is permitted provided that credit of authorship is provided and linked back to the source.


  1. I was bitten once by a black widow that found her way into my bed. I was sleeping and don’t remember the bite itself but I must have flinched in my sleep when she bit me because I found her dead (squished) when I woke up. She got me on the foot, which was swelling and getting painful (understatement). I cleaned the bite area with soap and water, worked some anti-septic into the bite holes as best I could, then bandaged it. Within a couple of days my foot was fine except for some dead, dry skin right around the bite. I’m no worse for wear but I hope never to repeat that experience. (As they say, “everything in AZ bites, stings, stabs, or pokes you”)

  2. I’ve was once bitten in the heal by a male tarantula (stepped on him outside the house at night in bare feet…Stupid Me!). He was just minding his own business trying to find a female and I stomped on him while taking the dog out to pee. It hurt like the dickens for about 3 hours. Nothing much to be done for it except to elevate leg and put an ice pack on it.

  3. This is a great article! If only everybody in the desert southwest would read it and watch their “P’s & “Q’s” around all of the deadly or dangerous critters. During one of the snake shows at the Desert Museum, the reptile curator stated that the average profile of a rattlesnake bite victim was young, male, drunk, with tatoos. I found that amusing.

  4. There are over 1000 species of harmless bees in Arizona, just don’t mess with the Africanized variety.

  5. Thanks for an interesting article. I had bees in one of my trees and finally had to chop the tree down because it was destroyed. Not to worry you pseudo-environmentalist. I planted another one that I like better.

  6. Man from Boston: Hi, I just moved here.

    Wayne B (rain): You should become familiar with the desert. You can pick up a Kingsnake, a Tarantula or a Horny Toad, but don’t pick up a Rattlesnake, Scorpion or Gila Monster.

    Man from Boston: I ain’t pickin’ up nuttin’!

  7. I thought for sure that our politicians (Onerous Massego) would top the list. But they are seldom found outside the restaurants and bars that make up their native environment.

  8. Except for this article I would never have thought that Africanized Honey Bees were numero uno venomous!

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