How to Avoid Black Widow Spiders Bites While Hiking or Camping

Black widow spiders are common in Phoenix and the Sonoran Desert

Black Widow Spider
Marshal Hedin/Wikimedia Commons

Black widow spiders are common in Phoenix, Arizona, and in the Southwest U.S. in general. Nocturnal creatures, they hide in the dark recesses of garages, sheds, woodpiles, and are commonly found while camping or hiking. Less than 1 percent of all people bitten by this spider run the risk of dying, and most of them are saved with the use of an effective antivenin. In fact, only four people die on average annually from venomous spider bites (from all spider varieties) in the U.S.

If you are experiencing serious symptoms after being bitten by any insect including what you think may be a black widow spider, seek medical attention immediately or call 9-1-1.

Black Widow Spider Details

Females are the only member of the species that really bite. A black widow's body is glossy black (or sometimes brown) with the characteristic red "hour-glass" shape on the underside of its abdomen. A female can reach a half-inch in length with long, thin legs up to two times its body length. The abdomen is large and bulbous, rather teardrop in shape when viewed from the side, and ends with a pointed "spinneret." She will usually be found hanging upside down in her web with the red hourglass clearly visible.

The female will seldom leave the web. The female lays her eggs in a web sac attached to her web. She can be very aggressive in the defense of her eggs.

Black widows can be found in North America, from Canada to Mexico, and in the West Indies. There are a lot of black widows in Arizona and Phoenix. Twenty-two different types of black widow spiders live in all corners of Phoenix and the Sonoran desert.

To identify a black widow web, look for a web that appears as if it has been spun by a very drunk spider. The black widow typically spins a very messy-looking web that bears little resemblance to the stereotypical neat and symmetrical web of most spiders. If the spider is not hanging upside down from the web, more likely it is hiding at the outside edge of the webbing or even in a dark crevice or corner nearby.

How to Avoid a Bite

Black widow spiders rarely bite humans. If you think you see a black widow spider in its web, then leave the creature alone. Spiders, like almost all other animals, will avoid humans and will run away if any avenue of escape is left open to it. Do not allow children or anyone else to poke sticks into the web or otherwise annoy the spider. The animal may get angry or scared enough to bite. This is especially true if there is an egg case present.

Likely Encounters

Black widow spiders can be found all year round. Populations will peak during the warm months, which is when the last year's brood will mature and new eggs will be laid and hatched. Due to Arizona's mild winters, some will even survive the cold season outside but they will usually seek more protected places to spin their webs and may even try to move indoors.

If you're visiting Arizona for camping and hiking, then look closely before using an outdoor latrine. Black widows are commonly found in the comers and under the seats in these buildings. An encounter can be very dangerous (not to mention extremely painful and embarrassing).

Be especially watchful in isolated rustic cabins, storage buildings, attics, and crawl spaces. These are places that humans rarely go and their primary prey of insects is plentiful. In the house, they will often be found in the garage, the back of the pantry, or any comer that is out of the traffic pattern. Be extra careful when unpacking seasonal clothing or equipment. In the garden, you can find their webs between the interior branches of shrubs and trees. Instead of just grabbing unused pots, netting, or tools that are laying around, you should carefully examine each for webs, spiders, or other unwelcome critters.

Black Widow Spider Bite Symptoms

A black widow bite may feel like a pinprick, or it might not even be felt at all. Widow spiders inject a toxin that affects the nervous system (neurotoxin). Muscle and chest pain or tightness are some of the most common reactions to the black widow toxin. Although extremely painful and temporarily debilitating, fatalities from untreated widow bites are uncommon. The very old, very young, and those with a history of high blood pressure are at greatest risk. Prompt medical treatment can greatly reduce the danger.

You might notice two faint red spots surrounded by local redness at the bite. At first, there may be only slight local swelling. Pain usually progresses up or down the bitten arm or leg, finally localizing in the abdomen and back. There may be pain in the muscles and soles of the feet, and eyelids may become swollen.

Other symptoms may be nausea, profuse perspiration, tremors, labored breathing and speech, and vomiting.

In more serious cases, a weak pulse, cold clammy skin, unconsciousness, or convulsions may occur.

Treating a Black Widow Spider Bite

If you get bit, remain calm. If possible, collect the spider for positive identification and get medical attention immediately. If visiting in Arizona, you can call a 24-hour, toll-free number for access to the Banner Poison Control Center at 800-222-1222.

Clean the bite well with soap and water. Apply a cool compress on the bite to minimize swelling and keep the affected limb elevated to about heart level. Apply a mild antiseptic such as iodine or hydrogen peroxide to prevent infection. Don't try to suck out the poison. That doesn't work.

In severe cases, physicians can intravenously inject calcium gluconate to counteract most effects of the toxin. A black widow antiserum also is available.