The Arizona desert is home to the Centruroides sculpturatus, commonly known as the Arizona Bark Scorpion. Scorpions do not truly hibernate like mammals, but they enter a state of reduced activity to survive the change in seasons. This period of dormancy is a direct response to temperature fluctuations and significantly alters their presence in the environment.
Defining Scorpion Winter Dormancy
Scorpions are ectotherms, regulating their body temperature based on their surroundings. When temperatures drop, especially below 50°F, their metabolism slows down considerably. This state is better described as quiescence or brumation rather than true hibernation. This physiological change is triggered by the cooling environment and is a survival mechanism to conserve energy when food sources become scarce.
True hibernation involves a deep metabolic reset, where the animal’s body temperature and heart rate plummet to near-zero levels. In contrast, a scorpion’s dormant state is temperature-dependent and much less profound; they remain capable of movement if the ambient temperature rises. Their need for food and water is greatly reduced, and they will retreat to sheltered locations. Although most scorpions are solitary, the Arizona Bark Scorpion will often aggregate in groups of 20 to 30 individuals during this time, which helps them survive the cold period together.
The Annual Cycle of Scorpion Activity
The activity level of scorpions is closely tied to the temperature, with the most significant movement occurring when nighttime temperatures are consistently above 70°F. During the winter, generally from late November to February, their activity is minimal as they remain in their dormant state. They only become active if a warm day causes the temperature in their shelter to rise. This period is often when they seem to “disappear” outdoors.
As spring arrives and temperatures begin to climb, scorpions emerge from their shelters, and their foraging activity increases steadily. The peak season for scorpion activity in Arizona typically runs from late spring through early fall. The hot summer months see their highest activity. The summer monsoon season, with its increased moisture, can also prompt greater movement, sometimes driving scorpions out of their saturated hiding spots and into homes.
Activity begins to slow down again during the fall, as the days shorten and temperatures start to consistently drop below the optimal range. This is the preparation phase, where they actively seek out the secure, warm, and dry locations that will serve as their winter shelters. Understanding this annual cycle is important because while scorpions are less active in winter, the potential for an indoor encounter remains if they have nested close to or inside a home.
Winter Shelters and Hiding Places
When temperatures signal the onset of the cool season, scorpions seek out protected microclimates. Outdoors, this often means retreating under large landscaping rocks, finding cover under tree bark, or moving into woodpiles and debris piles where they are shielded from the elements. They may also utilize natural crevices like cracks in the ground or expansion joints in concrete slabs.
For homeowners, a significant concern is the scorpion’s tendency to seek refuge in structural voids. The Arizona Bark Scorpion is an excellent climber. They can flatten their bodies to fit through gaps as narrow as 1/16 of an inch, allowing them entry into wall voids, block wall fences, and attic spaces.
Attics are a common winter refuge because they often retain warmth. Scorpions found inside a home during the winter months are a strong indicator of a nearby indoor nesting group. While dormant, these clustered scorpions are still present; disturbing their hiding spot or a sudden indoor temperature spike can cause them to become active and move deeper into the living space.