Concerns about brown recluse spiders are common, especially regarding their presence in states like Arizona. Understanding the actual distribution of spider species and how to identify them can alleviate unnecessary worry. This information also clarifies appropriate actions to take if a spider bite is suspected.
Are Brown Recluses in Arizona?
The brown recluse spider (Loxosceles reclusa) is generally not native to Arizona. Its established range primarily covers the Midwestern and South Central United States, from Nebraska to Ohio and south from Texas to western Georgia. While individual spiders may be transported, they do not typically establish breeding populations in Arizona. The misconception about their widespread presence often stems from misidentification of other brown spiders or general media influence. Physicians in western states, including Arizona, sometimes misdiagnose other conditions, like bacterial infections, as brown recluse bites, further perpetuating this belief.
Arizona’s Native Recluse Spiders
While the brown recluse is not common, Arizona is home to native recluse species, primarily the Arizona recluse (Loxosceles arizonica) and the desert recluse (Loxosceles deserta). These spiders belong to the Loxosceles genus. The Arizona recluse is found throughout the state, especially in southern regions, while the desert recluse inhabits western Arizona, southern California, Nevada, Utah, and New Mexico.
These native recluse spiders prefer dry, undisturbed environments, often residing outdoors in woodpiles, under rocks, or in dead cacti. If they enter homes, they seek shelter in dark, cluttered areas like basements, attics, or storage boxes.
Their venom contains compounds that can cause necrotic lesions, leading to a condition called loxoscelism. While most bites are minor, some can result in a shallow open sore. In rare instances, systemic symptoms like fever, nausea, or more severe reactions have been reported, though these are uncommon.
Identifying Common Arizona Spiders
Identifying a recluse spider requires careful observation, as many brown spiders are often mistaken for them. Recluse spiders, including Arizona’s native species, possess a distinct “violin” shaped marking on their cephalothorax, with the neck pointing towards the abdomen. This marking can vary in intensity and may be difficult to discern for non-experts.
A more reliable identifying feature is their eye arrangement: six eyes arranged in three pairs in a semicircle. Most other spiders have eight eyes, typically arranged in two rows of four. Recluse spiders also have uniformly colored abdomens and legs, lacking distinct patterns, bands, or prominent spines. A mature recluse spider’s body typically ranges from ¼ to ½ inch, with a leg span up to 1½ inches.
Another common Arizona spider is the black widow (Latrodectus hesperus), recognizable by the female’s shiny black body and a red hourglass marking on her abdomen’s underside. Black widows typically build irregular, strong webs in dark, secluded spots. While their bite can be medically significant, they are not aggressive and usually bite only when threatened or disturbed.
Responding to Suspected Spider Bites
If a spider bite is suspected, immediate first aid can help manage symptoms. Clean the wound with soap and water, and apply a cold compress to reduce swelling and pain. Elevating the affected area may also be beneficial.
It is not always possible to definitively identify the spider that caused a bite, and many spider bites cause only mild symptoms. However, seek medical attention if symptoms worsen, if there is increasing pain, spreading redness, or if systemic symptoms such as fever, chills, body aches, nausea, or vomiting develop.
Medical consultation is advised if the bite area develops a blister, turns dark blue or purple, or forms an open sore. Do not attempt to self-diagnose the spider species; a healthcare professional can provide proper evaluation and treatment.