Scorpions are a natural part of the Arizona landscape. While they are present throughout the year, their activity patterns change significantly with the seasons and the intense desert climate. Understanding the specific conditions that trigger their movement helps people anticipate their presence and take effective steps to reduce encounters around their homes. This knowledge is especially relevant in the low desert areas where the most concerning species thrives near human habitats.
Understanding Peak Activity and Seasonal Triggers
Scorpion activity is primarily regulated by ambient temperature, as these arachnids are ectothermic. The season for peak movement and reproduction typically runs from April through October across the state. They become noticeably more active when the nighttime temperatures remain consistently above 70°F, which allows them to hunt and forage efficiently.
The highest levels of scorpion sightings and stings occur during the hottest months of July and August. Their metabolism is at its peak, and they are most lively in the range between 70°F and 90°F. The summer monsoon season also plays a significant role in increasing sightings. Heavy rains can flood their natural underground hiding places, forcing them toward higher ground and often pushing them into residential areas.
As the weather cools in late fall, scorpions begin to slow down and seek sheltered locations to conserve energy. When nighttime temperatures start to dip below 70°F, many scorpions, particularly the Arizona bark scorpion, move toward warmer structures. This search for stable temperatures often leads them to the interior of homes during the late fall and winter months.
Where Scorpions Hide During Active Periods
Scorpions are nocturnal, meaning they are most active after sunset when temperatures are cooler and they can avoid the intense daytime heat. They spend their days tucked away in a variety of dark, cool, and protected spots to prevent dehydration. This crevice-seeking behavior often brings them into close proximity with people.
Outdoors, scorpions commonly shelter under landscape materials like rocks, decorative stone retaining walls, and piles of wood or debris. They are frequently found beneath potted plants or concrete slabs that offer stable temperatures and moisture. The Arizona bark scorpion, the most common and venomous species in the region, is unique in its ability to climb. It can often be found resting on vertical surfaces like stucco walls or under the bark of trees.
When seeking shelter near or inside a home, scorpions exploit incredibly small openings. They can squeeze through gaps as thin as one-sixteenth of an inch, using entry points such as cracks in the foundation, poorly sealed utility conduits, and openings around doors and windows. Once indoors, they look for dark, undisturbed areas, including the inside of shoes, piles of clothing on the floor, or wall voids behind baseboards.
Home Prevention and What To Do If Stung
Effective scorpion control begins with diligently sealing the exterior of the home to eliminate potential entry points. Homeowners should apply weather stripping to doors and windows and use caulk to close cracks and crevices in the foundation and exterior walls. Replacing standard white outdoor light bulbs with yellow or amber light bulbs can also help, as white light attracts the insects that scorpions prey upon.
In the yard, eliminating outdoor harborage areas is an important step in reducing the local scorpion population. This involves removing clutter like lumber scraps, stacked bricks, and overgrown vegetation that touches the structure of the house. During evening hours, a UV blacklight can be used for inspection. Scorpions fluoresce a bright greenish-yellow color under this light spectrum, making them easy to spot and remove.
If a scorpion sting occurs, the first step is to immediately call the Arizona Poison and Drug Information Center at 1-800-222-1222 for professional medical guidance. For a typical sting, immediate first aid involves cleaning the wound thoroughly with soap and water and applying a cool compress or ice pack to manage the localized pain and swelling. Over-the-counter pain medication like acetaminophen or ibuprofen can be used for minor discomfort.
In North America, only the Arizona bark scorpion is considered medically significant, particularly for vulnerable populations like infants, small children, and the elderly. Immediate medical attention should be sought if the individual experiences severe symptoms such as muscle twitching, difficulty breathing, or vomiting. Antihistamines or epinephrine should not be used, as they can sometimes worsen the effects of the scorpion’s neurotoxin.