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The Desert Southwest, or more specifically, Arizona, does not have the famous Brown Recluse (Loxosceles reclusa) spider, but if you are getting your information from certain medical professionals, the internet (current source aside) or a “know it all” neighbor, you may believe otherwise.

We do, however, have a very close relative.  The Arizona Brown Spider (Loxosceles arizonica) makes its home here and is nearly identical in appearance to its cousin. The Arizona Brown’s markings are much less striking.  The main difference between the two is very subtle…think of our spider as being a less Hollywood than its more celebrated relative.

This family of spiders (Loxosceles) occurs throughout the southern United States, their range stretches as far down as Mexico and Central America. Not all are desert dwellers, but Arizona is home to several species of Loxosceles.  Recently, in conjunction with concerns regarding climate change, issues have been raised regarding the possibility of recluses spreading farther due to warmer air carrying them faster. This however, cannot be true.  “Ballooning”, or travelling via small web generated parachutes, does not occur within any recluse species.  Populations are remaining in the same spaces where they have always dwelt.  Migratory patterns cannot be associated with recluse spiders.

Recluses are secretive spiders.  They prefer to secrete themselves in desert debris, around dwellings or in other areas not frequently disturbed. The recluse spider relies on its web to trap its prey, catching insects in uneven and sticky weavings left created under rocks, cacti and other native debris. The spider is usually found in the middle of its web, which usually contains the leftover remains of previous meals. The Arizona Brown prefers to dine on ants (especially those active at night) such as carpenter ants. Because it waits for its prey however, the recluse will eat whatever comes into its web, and is not particularly discriminatory in its tastes.

Female Arizona Brown spiders lay their eggs in cases and once hatched, the young may live, depending on conditions for two or three years.

The Dangers of the Arizona Brown Spider

The spiders themselves are rarely seen, but their bites can be a distinguishing factor by which they are identified.

Many types of skin wounds are mistaken for or assumed to be the result of a recluse spider bite. Many times a month our office takes calls from customers claiming that Doctors, EMT’s or some other knowledgeable source has told them with authority that they have a recluse bite.  Many different things can mimic the lesions of a bite of the recluse spider, including Lyme disease, various fungal and bacterial infections, just to name a few. It is critical to associate the spider directly with the bite to begin appropriate treatment.  The biggest mistake is the failure to consider alternative diagnoses if no spider was seen in association with a wound or lesion.

The recluse spiders come by their name honestly.  As their name indicates, they are not to be found readily and prefer to be out of the way.  Bites most often occur as a result of the spider being trapped against the skin, when someone reaches into an unseen area where the spider may be resting in its’ web, or if it were to become entangled in clothing.

When bites occur, they can be generally categorized into one of the following groups:

    • Unexceptional:  Self-healing,  causing only minute damage
    • Slight:  Self-healing damage with some itchiness or redness, perhaps some aggressive venomous behavior and potentially accompanied by a mild lesion.
    • “Dermonecrotic” (Flesh Consuming):  This is the unusual but, “classic” recluse bite, producing a destructive skin wound. It is estimated that 66% of these wounds heal with no further issues. In extreme cases, the wound may be up to 40 centimeters wide and last for a few months. When it heals, it will leave a permanent scar. This reaction may be due to an allergy to the venom and not the venom itself
    • Systemic – This is an extremely rare reaction. This result is a sometimes fatal reaction to venom being introduced directly into the bloodstream. This reaction is more common in grossly overweight victims, because the venom destroys fatty tissue readily. It is more often fatal in children.


Most bites are unexceptional or slight, resulting in no noticeable long term issues at all.

Are You Protected?

The Arizona Brown Spider gets a lot of attention, and must be taken seriously.  If you believe you have a problem with these pests around your home, call University Termite & Pest Control and have one of their professionals come over and take a look.  They have the skill and knowledge to identify them and make a correct diagnosis the first time, every time.

University Termite & Pest Control, The Ones Who Know….


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