How do I keep scorpions out of my house in Arizona?

Scorpions in an Arizona house aren’t a sign that something is uniquely wrong with the property. They’re in every yard in the valley. The difference between a house that has scorpion problems and one that doesn’t usually comes down to two things: how many gaps the structure has that they can get through and how much the outdoor conditions around the house are encouraging them to try. Both are addressable, and neither requires ongoing chemical treatment as the primary strategy if the physical side of the problem gets handled first.

Sealing

Bark scorpions, the species responsible for most Arizona encounters, can compress their bodies through a gap roughly the size of a credit card. That’s the physical reality that makes the standard “check for gaps” advice feel inadequate until the actual gap size is understood. A visible gap under a door, a space around a pipe that looks minor, a crack where the foundation meets the exterior wall. Any of these is an open door in functional terms.

Door sweeps are the highest-return sealing investment and the most commonly neglected. A sweep that was installed at construction and hasn’t been replaced since has almost certainly lost the full-contact seal across the bottom that makes it effective. Check each exterior door by looking at the threshold gap from inside with the door closed. Any visible light means scorpions can get through. The corners are where sweeps fail first and matter most. Replace the entire sweep rather than trying to adjust a worn one, and check the fit after installation rather than assuming it’s sealing correctly.

Weatherstripping on the sides and top of exterior door frames degrades at a slower rate than door sweeps and gets replaced less often because the failure is less visible. Run a hand along the door frame with the door closed and feel for gaps rather than looking for them. Compression weatherstripping that’s been cycled through years of temperature swings in an Arizona climate loses its elasticity and stops creating the barrier it appears to create.

Utility penetrations are the sealing category that produces the most surprised homeowners when they actually look at them. The gap around the plumbing under the kitchen sink, the space where the dryer vent exits through the exterior wall, the opening around electrical conduit entering the garage, and the gap where refrigerant lines come through the wall to the AC system. These get made with a specific pipe in mind, and the space around them gets sealed imperfectly at installation or not at all. Expanding foam or caulk on accessible penetrations closes these off in an afternoon. Hardware cloth over weep holes in brick exteriors covers the entry points that are intentional gaps in the structure, rather than installation oversights.

Garage doors need attention at the perimeter rather than just the bottom sweep. The side seals and top seal on a garage door in service for several years develop gaps that scorpions use regularly. The bottom sweep gets noticed and replaced. The perimeter seals don’t, and the scorpion that’s been getting in through the side seal while the bottom gets checked every few months continues to get in.

Treatments

Sealing is the primary strategy. Treatments are the secondary layer that reduces the outdoor population pressure against the sealed structure. The distinction matters because chemical treatment without sealing produces temporary results. The population gets knocked back and recovers, and the gaps that allowed entry before allow it again. Sealing without treatment still leaves a significant outdoor population finding whatever gaps remain.

Pesticide application around the foundation perimeter, along the base of exterior walls, and at the entry points that couldn’t be fully sealed creates a chemical barrier that affects scorpions making contact with it. Scorpion metabolism processes some pesticides differently than other insects. They’re more resistant to certain chemical classes, and the residual effectiveness varies by product and conditions. Professional pest control services that specifically treat for scorpions use products and application methods calibrated for the species rather than general insect treatments that underperform against scorpions.

UV blacklight inspection is the tool that makes treatment more targeted. Scorpions fluoresce bright green-white under UV light in darkness, which makes an evening inspection of the exterior perimeter diagnostic rather than speculative. Where they’re concentrating, which walls they’re working along, whether they’re finding the foundation or the garage entry or a specific penetration point. All of this is visible with a blacklight that costs under twenty dollars. Treating and sealing based on where they’re actually active rather than where they might be active produces better results with less material.

Scorpion Prevention

The outdoor conditions around the house determine how much pressure the sealing and treatment have to handle. Scorpions follow their food supply, and the food supply is other insects. Crickets, roaches, silverfish, the insects that accumulate in organic debris, moist areas, and the kind of ground cover that creates stable harborage close to the structure.

Bark on the ground against the foundation, dense low plantings touching the exterior wall, firewood stored against the house, and leaf litter in corners of the yard. All of these create conditions that support the insects scorpions hunt and create scorpion harborage close to entry points. Moving organic material away from the structure, maintaining a clear zone between plantings and the exterior wall, and eliminating moisture sources near the foundation. These don’t eliminate scorpions from the yard, but they reduce the conditions that concentrate them near the house.

Lighting draws insects at night, and insects draw scorpions. Yellow or sodium vapor bulbs at exterior entry points attract fewer insects than standard white bulbs, which reduces the food source concentration around the doors that scorpions are already investigating for entry gaps. It’s a marginal contribution compared to sealing, but it costs nothing after the bulb swap.

The combination that actually works long term is physical sealing that makes the structure difficult to penetrate, chemical treatment that reduces the outdoor population and creates a barrier at remaining gaps, and yard management that reduces the conditions drawing scorpions toward the structure in the first place. Any one of these alone produces partial results. All three together change the situation in a way that holds across seasons rather than requiring repeated responses to the same problem.