Are there brown recluse spiders in Arizona?
Written by the Hydra Pest Control team, Arizona-licensed (license #9790)
Last reviewed:
Short answer
Not established ones. University of Arizona Extension says the true brown recluse does not occur in Arizona, and University of California IPM says its range is the south central Midwest, from southeastern Nebraska to southwestern Ohio and south through Texas to north Georgia. Arizona does have native recluse spiders, mainly the Arizona recluse and the desert recluse. UC IPM says desert recluse venom is similar to the brown recluse's and should be considered of equal potency.
Arizona context
Anywhere in Arizona, including the Gila Valley, Sierra Vista and the White Mountains, a spider called a brown recluse is almost certainly a native recluse or a look-alike. University of Arizona Extension says the recluse spiders found in Arizona are often mistakenly called brown recluses, and that the most common Arizona species are Loxosceles arizonica and L. deserta. UA Extension names the Arizona recluse and the western black widow as the two most common venomous spiders in Arizona.
If you think you found a recluse
- Don't handle it with bare hands. University of Arizona Extension recommends gloves and a long-sleeved shirt when working in spider areas or handling firewood
- If you can, capture the spider in a jar so it can be identified. UA Extension says finding the spider helps in diagnosing and treating a bite
- Shake out clothes and shoes that were left on the floor before you put them on
- Move the bed away from the wall and remove bed skirts and anything stored under the bed
- Move woodpiles, boxes, plywood and tires away from the house, and seal cracks around doors and openings for wiring and plumbing
Brown recluse vs. Arizona's native recluses
University of Arizona Extension says the true brown recluse, Loxosceles reclusa, does not occur in Arizona, and that the closely related Arizona species are quite similar to the brown recluse and can be told apart only by an expert. University of California IPM says the brown recluse is the most widespread North American recluse and lives in the south central Midwest.
Arizona's recluses are desert species. UC IPM says the desert recluse, Loxosceles deserta, is found mostly in the Sonoran and Mojave deserts, and that its venom should be considered as potent as the brown recluse's. It also says the violin marking is very faint to nonexistent on several southwestern recluses, including the desert recluse.
Why so many brown recluse reports? A 2005 study in the Journal of Medical Entomology looked at 1,773 arachnids that people in 49 states sent in as suspected brown recluses. From 25 of 29 states completely or almost completely outside the range of recluse spiders, no recluses were submitted. The study concluded that brown recluses are virtually limited to their known range, even though the public believes they live across wide areas of the U.S.
How to tell a recluse from a look-alike
Count the eyes. University of California IPM says this is the most definitive feature: most spiders have 8 eyes, usually in 2 rows of 4, while recluses have 6 equal-sized eyes arranged in 3 pairs. University of Arizona Extension says you will likely need a hand lens to see them.
Then check the body. UC IPM says a spider has to have all five recluse features: 6 eyes in pairs, a uniformly colored abdomen with fine hairs, no spines on the legs, uniformly colored legs and a body no more than 3/8 inch long. Many tan or brown spiders get mistaken for recluses, including wolf spiders, sac spiders, ground spiders and grass spiders, but UC IPM says these have 8 eyes and can be quickly ruled out.
Don't go by the violin. UC IPM says the presence or absence of the violin marking is not a reliable way to identify a recluse, and that people often see violins on spiders that aren't recluses.
When professional service is warranted
Call if you find recluse spiders more than once. University of California IPM says recluse populations are usually dense: if you find recluses, you don't find one, you find many. University of Arizona Extension also says most recluse spiders live in groups. If a spider bite causes pain, concern or a reaction, UA Extension says to contact your physician or the Arizona Poison and Drug Information Center at 1-800-222-1222 as soon as possible. UC IPM warns that many skin lesions are misdiagnosed as brown recluse bites, with potentially serious consequences, so have a wound checked rather than assuming. This is general information, not medical advice.
How Hydra handles it
Our Service Pros identify which spiders you have before treating, then treat hiding spots and entry points and help reduce the insects spiders feed on. Not sure what you found? Call or text your local office to reach an Office Pro, or ask for a free custom quote.
Frequently asked
Do brown recluse spiders live all over Arizona?
No, that's a myth. University of Arizona Extension says the true brown recluse does not occur in Arizona. What Arizona has are native recluses, most commonly the Arizona recluse and the desert recluse, which UA Extension says are often mistakenly called brown recluses. A 2005 study in the Journal of Medical Entomology found that brown recluses are virtually limited to their known range, even though people believe they live across wide areas of the U.S.
Are Arizona recluse spiders dangerous?
They can be. University of Arizona Extension says a few desert recluse species and the western widow are the only Arizona spiders whose bites require medical treatment, and University of California IPM says it's best to assume all recluse spiders can cause skin damage. Most bites aren't severe, though: UC IPM says about 10% of brown recluse bites cause moderate or greater tissue damage, and the vast majority heal well without medical intervention. If a bite causes pain, concern or a reaction, contact your doctor or call Poison Control at 1-800-222-1222. This is general information, not medical advice.
Does a violin marking mean it's a recluse?
No. University of California IPM says the violin marking is not a reliable way to identify a recluse. It's very faint or missing on several southwestern recluses, including the desert recluse, and people often see violins on spiders that aren't recluses. Check the eyes instead: recluses have 6 eyes in 3 pairs, while most spiders have 8.
Can a brown recluse bite diagnosis be wrong?
Yes, often. University of California IPM says many skin lesions are misdiagnosed as brown recluse bites, with potentially debilitating and potentially fatal consequences, and University of Arizona Extension says bites from blood-feeding insects such as kissing bugs and bed bugs are often mistaken for spider bites. If you can, capture the spider in a jar so it can be identified. If a wound is getting worse, see your healthcare provider, or call Poison Control at 1-800-222-1222 with questions. This is general information, not medical advice.
Related on this site
Related questions
References
- University of Arizona Cooperative Extension: Pests of the Home and Garden (AZ1677)
- University of Arizona Cooperative Extension: Spiders (Backyard Gardener #177)
- University of California IPM: Brown Recluse and Other Recluse Spiders Pest Note
- Vetter, R.S. (2005). Arachnids submitted as suspected brown recluse spiders. Journal of Medical Entomology 42(4):512-521
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