This summer we learned a little about the most dangerous snakes in the Southwest and how we can guard against a little critter spoiling your vacation in the desert. Same objectives, but we are going to look into poisonous spiders this month, as they are all around us, here in the Southwest!

And guess what, in MOST cases none of them are deadly. They either do not have the potency in their venom to do the trick or they cannot get the volume of venom home that would be necessary to do the job on a human being.

Their venom is used to subdue other pray like insects and small animals. They mostly catch their pray outside the Web, which is really a nesting area.

There are 4 species of spiders to worry about across the southwest from Texas to San Diego. Those species are tarantulas, the brown recluse, the brown widow and the black window.

1: Tarantulas:

There are over 800 species worldwide. Tarantulas are relatively new to Southern California. Brought here as pets, in wheel wells or concealed in clothing. These are just a few of the many ways this spider migrated to Southern California.

Tarantulas are shy, prefer to live in solitude and will only attack if they are disturbed or when guarding their young ones. Tarantulas like crevices, burrows, being under ground, under anything like leaves and tree bark, sloped areas like mountains, foothills and desert basins.

Its web is very disorganized but strong, thick and sticky. When pray wanders into the web area, vibrations from the strands of the web warn the spider lying in wait and the Tarantula will immediately attack.

They will attack anything up to their own size. Plus they are not afraid to wander far from their web in search of pray.  But humans are relatively safe as their venom isn’t very potent and you really have to press one to attack.

Most of the time tarantulas can be handled without them biting or being defanged and they supposedly make great pets. Females are much larger than males. Tarantulas can be 1 to 5 inches in body length and with their legs they can span anywhere from 5 to 10 inches. Females can be tan to reddish brown and black, while males are usually black and much smaller. Males do not bite. Sometimes, if the female didn’t like the sex from her chosen, she will eat the male.

  2 & 3: The Brown Recluse and the Brown Widow:

There are just 13 or less verities of the BROWN SPIDER all over the United States. There is even an Arizona Brown Spider. All of them have venom with a potency that varies from mild to severe; but most of the time these bites can damage a lot of tissue around the bite area but are not usually life threating.

The best way to tell the difference between the two spiders is their legs, as the Brown Recluse will have a brown body with furry brown legs and the Brown Widow will have a brown body but alternate bands of black and white on their legs with no fur.

The Brown Widow is slightly smaller than the Brown Recluse with bodies that range from a ½ inch to just 3/8 of an inch in length. But with their legs they can be 1 to 3 inches in circumference. Most have an hour glass shape in red on their backs.

Brown Spiders like their webs to be close to the ground, in undisturbed places as they are very shy and will only attack if contacted. They will hunt mostly at night and then take refuse in clothes lying on the floor or anywhere low that they can hide during the day, thus the name “Recluse”.

They like to run in large numbers, so if you see one beware, there is most likely more. So shake anything out that has been laying on the floor before putting it on when you are out there.

 4: Black Widow:

Black Widows venom is considered the most deadly of all animals in the Southwest. There bite is 15 times more deadly than the Prairie Rattlesnake and still, no one has died from a Black Widow bite in over 10 years.

Only the female is dangerous, the male is half her size and does not have venom. Their bodies are .5 inch to 1.5 inches in length with a large sack on their backs and legs that will make the Spider’s overall size to be under 4 inches. Of course they are black in color.

This spider is found all over the southern half of the United States from about the 45th parallel and south. The Black Widow is abundant in all 4 southwestern deserts.

They can be found on the ground or up off the ground. They like to hide under rocks or ledges, plants and other debris, mostly on the ground. The spider spins large shapeless, erratic, rough and sticky webs and their silk is the strongest of most other spiders in the world but again, the web is used mostly for nesting.

Like its fellow venomous arachnids it is a shy nocturnal being. Like the Brown Recluse the female Black Widow will occasionally eat her suiter.

What to do if bitten?

1: DO NOT suck the venom out with your mouth. Bring a snake bite kit with you, which has a venom suction device. Bring lots of water with you too.

2: Wash the bite with soap and water.

3: Apply ice. Ice will slow the movement of the venom through the body.

4: Apply an antibiotic cream or lotion to the bite area.

5: If the bite is on a limb, elevate the area.

6: Try to capture the spider in a glass jar if you have one, so the medical person can determine exactly what venom he is facing.

7: Get victim immediate medical care. Sometimes venom can do strange things. The bite may appear almost inconsequential now and 24 hours later the area surrounding the bite can become ulcerated and very painful and more serious effects may occur. Poison Control center 1-800-222-1222.

Disclaimer: The information provided in this article is for reference purposes only and should not be used to diagnose or treat a patient in a medical emergency. This article is not a substitute for professional medical care.


Thirteen Venomous Animals of the Southwestern Desert. Which is more dangerous?


Brown Recluse Spider:

Brown Widow:

Black Widow Spiders:

Black Widow Spider bites: