Centipedes are common across Arizona. The state’s diverse habitats, from the low deserts to the higher-elevation scrublands, support several species. Some centipedes are quite large, making them a source of concern due to their intimidating appearance and ability to deliver a painful venom injection.
Centipede Species Common to Arizona
The most prominent species is the Giant Desert Centipede (Scolopendra heros). This centipede can measure up to eight inches in length, making it one of the largest in North America. Its coloration often features a rust or orange body with contrasting black head and tail segments, and pale yellow or orange legs.
Another prominent species is the Common Desert Centipede (Scolopendra polymorpha). This centipede generally reaches four to five inches, appearing smaller than the Giant Desert Centipede. Its body color is highly variable, ranging from brown or tan to tones of blue, green, or yellow, sometimes with dark banding that gives it the nickname “tiger centipede.”
A third, smaller species is the House Centipede (Scutigera coleoptrata), which is only about one to two inches long. This species is easily recognized by its yellowish body with dark stripes and extremely long, delicate legs that give it a much larger appearance.
Where Centipedes Live and When They Are Active
Centipedes across Arizona are nocturnal hunters. They spend the daylight hours sheltering in cool, moist, and dark locations to conserve body moisture and avoid the intense desert heat. Their natural hiding spots include areas under rocks, fallen logs, leaf litter, and yard debris.
These arthropods are well-adapted to arid conditions but seek out microclimates with higher humidity. This need for shelter sometimes brings them into contact with human dwellings, particularly when seeking prey or refuge from extreme weather. They may enter homes through small cracks and crevices, often ending up in damp areas like basements, closets, or laundry rooms. They are more active during the warmer months.
Assessing the Risk of a Centipede Bite
Centipedes do not bite with mouthparts. Instead, they use a pair of modified front legs called forcipules to pinch and inject venom. These specialized appendages function like hypodermic needles, leaving two distinct puncture marks. While the venom is used to subdue prey, it is rarely life-threatening to healthy humans, even when delivered by the Giant Desert Centipede.
The primary symptom of envenomation is intense pain, followed by localized swelling and redness. This discomfort can last from several hours to a few days, similar to a severe bee sting. To treat the wound, the area should be cleaned immediately with soap and water to minimize infection risk.
Applying a cold compress or an ice pack wrapped in a cloth for ten-minute intervals can help reduce pain and swelling. Over-the-counter pain relievers or antihistamines may be used to manage local symptoms. Seek professional medical attention if the pain is unbearable or if systemic symptoms develop, such as difficulty breathing, widespread hives, dizziness, or throat swelling. Medical consultation is recommended if signs of a secondary infection, like increasing redness, pus, or fever, appear days after the initial event.