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What to Know About Our Desert Pests and Critters

Once again, we review our desert pests, and some of the concerns we have living in the southwest. While there are many animals that fit this definition of “pest”, we’ll talk about those which are native to the Arizona desert, and how to avoid injury if encountered. Where in our Arizona desert would we find these desert critters? What actions provoke injury to perceived foes? What toxins are released and how do they affect us? What should we do if bitten stung or otherwise injured?

The Gila Monster (The beautiful, beaded lizard)


The Gila monster is a very large lizard. They are found in northern Mexico and the American Southwest. They are easily recognizable by having an entire body covered in pink, yellow and black scales. Gila Monsters move slowly and awkwardly and have poor eyesight. They rely therefore on smell and taste to hunt. Gila Monsters do not attack humans unless they feel threatened. A Gila Monster hissing is a sure indication it feels threatened. The attack may happen within seconds of that hissing warning.  You can appreciate the beauty of the lizard from a distance.

Gila Monsters live in burrows and under rocks. Gila Monsters bites can occur after being startled by a hiker kicking at a rock. Gila Monsters are seen outside of burrows or away from rocks when searching for food, or heat. A threat to a location where a Gila monster is basking in the heat, or to a food source could provoke an attack. A Gila Monster away from its normal lodgings may be presumed to be hungry and wary.

If you are bitten by a Gila Monster, remain calm. According to Arizona Poison and Drug, try to undo the Gila Monster’s grip by prying open the jaws with a stick and position yourself so that the Gila Monster is grounded. Keep the injured area beneath the level of the heart. Go to a Medical Facility Immediately. What not to do if you are bitten: Do not apply ice. Do not apply a tourniquet or anything constrictive. Do not suction the wound. Do not apply any medications or alcohol to the wound,

A Gila Monster bite is described as very painful and very forceful. Gila Monster toxin released at the time of the bite is extremely powerful. In fact, the toxicity of a Gila Monster bite ranks on a level equal to that of a rattle snake. Why then is the bite not fatal? The answer is an interesting variation in efficacy of poison delivery systems slow and spreads locally, mostly confined to the victim’s skin. The rattle snake poison, on the other hand, is injected, spreads deeply and rapidly, and thus is lethal.

Nonetheless, the Gila Monster poison does cause sweating, vomiting, dizziness, and bruising. Any bite by a Gila Monster requires immediate medical attention.  Finally keep children and pets away from a Gila Monster.

Like many desert pests, bees defend themselves by injecting venom. A single bee sting does not contain a quantity of venom that can kill a human. The exception to this, are those bee stings that provoke severe allergic reactions, specifically anaphylaxis to bee venom. It should be noted that bees are not generally aggressive. Bees are, however, very defensive. Bees will defend their nest and their colony. Bee nests can be found anywhere. Common sites for nests are tree trunks or a hole at the base of the tree. An opening in or around a residence, where bees are actively entering and leaving, can be indicative of a nest.  Large hives have been found inside the walls of homes where an exterior opening was present.

Bees DHFD May 2023

A single bee when threatened will release its stinger. This in turn releases pheromones that singles danger and alerts other bees. Once the source of the perceived danger is identified the bee will travel towards the threat. The bee will attack, and sting. The stinger once inside the victim will pump out venom and release alarm pheromones, which summons other bees. Multiple bees then swarm the perceived enemy. Quantitatively the amount of venom released can be fatal. If you unintentionally disturb a swarm of bees, such as a nest, run as fast as you can until you can reach an enclosed shelter such as a car or building.  Keep running until you are no longer being followed. Swarms have been known to pursue for up to a quarter of a mile. Bees, unlike wasps and hornets have a barbed stinger. When a bee stings, the stinger and parts of the bee’s digestive system are ejected. The bee after stinging dies. This is different from wasps and hornets which have straight and thus reusable stingers that can deliver multiple stings.

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If you are stung by a bee:  Stay Calm.  The stinger and venom sac should be carefully removed immediately. This will stop the continuous release of venom and pheromones.  To remove the stinger, scrape the overlying skin with a fingernail, or rub gauze over it. Do not use tweezers as the squeezing action may cause more venom to be released.  Wash the area with soap and water.  Apply ice or a cold pack.  Seek medical attention immediately for multiple stings or you suffer a severe allergic reaction.  Symptoms may include severe itching, hives, skin color changes such as flushing or paleness. Seek medical attention for any of these symptoms: Difficulty breathing, and/or face and tongue swelling. Systemic symptoms such as dizziness, fainting nausea, vomiting, diarrhea, loss of consciousness require immediate medical attention.

There are approximately 45,000 known species of spiders. While it is true that almost all spiders have poison glands, most do not bite humans. Spiders do prefer dark places, often found in nature under rocks or dead trees. Spiders are found in our gardens, and enter our homes, appearing in drawers, closets, and clothing. Spiders do not bite generally, except when they perceive a threat.. Arizona has three types of spiders we’ll review below, whose venom can cause nasty reactions at bite sites. Fatalities from these bites is rare, as the amount of venom delivered is small. Children can have severe reactions to spider bites due to their smaller size.

Black Widow Spider

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These spiders are described as shy, and bite when they feel threatened. Their venom is much more toxic than that of a rattlesnake, but as noted delivered in much smaller amounts. Commonly there is pain at the bite site. Only 1 - 2 % of victims have seizures which can be life threatening. Bite victims are occasionally hospitalized for pain management from the bite itself and for muscle spasms.  A black widow spider bite initially may appear to be nothing more than pin prick.  Symptoms can follow between thirty to sixty minutes after the bite.  Severe symptoms can include muscle spasm in area of the bite, that may spread to the abdomen from a lower extremity bite or chest from an upper extremity bite. Rarely do seizures occur. Sweating, fever, elevated blood pressure nausea and vomiting can also occur. Symptoms can last for two to three days. See below for what to do if bitten by a spider.

Brown Recluse Spider

Brown Recluse Spider DHFD May 2023

Brown recluse spider bites: These bites are slightly different than black widow spider bites. Initially a bite may not be noted or may be slightly painful. The skin will become red and tender where the bite occurred. There is no immediate widespread effects of the bite. Within three to seven days symptoms may present as pain in the joints, a body rash, fever and chills and nausea and vomiting. The skin overlying the bite may become necrotic and ulcerate.

Healing can be slow from these wounds often requiring several weeks. Medical attention should be sought for management of these bites and treatment of the wound.


Scorpian DHFD May 2023

These little pests are found primarily in Southern USA. Of the over 15,000 species of scorpions, thirty of these are venomous. Unlike spiders who defend themselves by biting, scorpions sting. The stingers are located at the end of the tail, which is quite flexible. They are territorial and often spend a lifetime in the same territory. They are described as nocturnal, and solitary. Scorpion stings are not generally lethal. Most species in the United States do not cause a life threatening reaction. Generally, the sting causes a skin reaction at the sting site. Life threatening symptoms from a sting, can include internal bleeding, tremors, muscle pain and weakness. Scorpions do not lose their stingers and thus are capable of stinging multiple times. The venom becomes weaker with each sting. There have been no deaths reported from scorpion stings in Arizona since 1968. There is antivenom available for Scorpion bites.

Prevention of Spider Bites
Prevention for any spider bites focuses on awareness of what triggers the spider’s defenses. Prevention involves being prepared for accidently disturbing a spider’s habitat. If outdoors hiking or gardening, or doing yard work, look for rocks cervices and wood piles a spider may be hiding in. Wear gloves if gardening, wear long sleeved shirts, tuck pants into socks. Clear away old furniture, junk, newspapers, magazines, or anything that will provide a nesting place inside the house and garage. If there are cracks in walls, or crevices fill them in. Good insulation is important for doors and windows, attics, and crawl spaces. Look at the drawers you are opening prior placing your hand in the drawer. Shake out your shoes or clothes if you are aware of spiders in your closet.

What to Do If Bitten By a Spider
Most important, Stay Calm. (Sound familiar). Clean the wound with soap and water. Apply cold compresses or ice. Tetanus shot is recommended if booster is not up to date. For severe pain and/or systemic symptoms seek medical attention. (There is an antivenom for Black Widow Spider bites which is effective within 48 hours of a bite). There is no anti-venom vaccine for brown recluse spider readily available in the United States. There is a anti -venom vaccine available for Scorpion bites.

Snakes in Arizona

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Snake encounters are more likely to occur in the spring and summer, taking advantage of warmer weather. Natural habitats of snakes include scrublands, grasslands, rocky canyons ledges, and hillside caves. Rattlesnakes are attracted to the heat of rural roads and can been seen soaking up the warmth on these roads when the weather is hot.

Snakes, as with other desert critters do not target humans as prey. They do however react quickly to perceived threats, striking and injecting venom through their fangs. Snake venom is produced by salivary glands located in the back of the snake’s head. When the snake bites, muscles in the back of the head contract, this squeezes muscles that propels venom into the fangs which is then delivered into the victim. Effectively this is similar to delivering an injection through a hypodermic needle. The composition of the venom differs amongst snake species. Antivenom differs depending on the specific snake species. A snake bite victim that can accurately describes the snake or can take a picture without delay in getting help, will have a better chance of receiving the appropriate antivenom. Snake venom effects the nervous system, circulatory system, and muscular system. As a result, nerve cells in the brain do not communicate correctly with the rest of the body. Red blood cells are damaged and unable to clot, causing bleeding and very low blood pressure.

Muscle cell damage prevents muscle contraction and destroys muscles cells. Antivenom is treatment is lifesaving. The most frequent complaint about antivenom is how extraordinarily expensive it is. Prevention of snake bites is truly the best medicine. Prevention of bites in general is the same as discussed for the other bites and discussed in this article.

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What to do if bitten by a snake:

  • One immediate goal is to get to a hospital as quickly as possible. Fatality rate is much lower when medical care is received in the first six hours.
  • A second immediate goal is to stay calm. Knowing that 70% of snake bites are not fatal, and that 50% of snake bikes are “dry, meaning venom was not injected, may help keep you calm.
  • Keep the affected limb immobilized.
  • Remove any clothing or objects such as rings, watches, and jewelry that may be restrictive once swelling begins.
  • Identify the upper edge of the swelling furthest from the wound and mark it, recording the time. Continue to mark the swelling as it progresses. It is also helpful to record the circumference of the swelling and track this as well.
  • Exercise will increase venom absorption. The victim should not exert themselves. Did we say, STAY CALM.
  • DO NOT apply pressure or compression bandages.
  • DO NOT use a tourniquet.
  • DO NOT attempt to extract the venom.
  • DO NOT wash, irrigate, or manipulate the wound.

Wrapping It All Up

We’ll wrap up here with some interesting research done in regard to the “Pests and Critters” we’ve mentioned. Research in the development of antivenom has led to very important pharmaceutical applications. Identifying specific components of venom and modifying it to remove toxicity has been hopeful:

Gila Monster Venom contains a protein that improves insulin secretion in response to meals, mimicking a hormone in human intestines that that controls glucose through insulin secretion and slowing stomach emptying, and suppressing appetite. Exenatide, brand name Byetta, is the derived from the venom in Gila Monster saliva.

Bee Venom in lab studies has demonstrated helpful benefits as anti- inflammatory, anti-antioxidants, and possible helpful in cancer therapy. Research is ongoing.

Spider venom has been shown to be effective in pain control. Tarantula venom has shown promise as an alternative to opioids.

Scorpion venom has pain control applications, as well as anti-cancer properties.

Snake Venom has been modified and shown to be beneficial for treatment of brain injuries and strokes. Blood thinning properties in snake venom have been modified and used as anticlotting agents. Cobra venom modification has promise for treatment of Parkinson’s Disease and possibly Alzheimer’s.

As always, be careful as you work, play, and enjoy our beautiful Southwest. And spread the word about what you may now know about our desert pests and critters with family and friends.