Why are there so many spiders in my house in the fall?
Written and reviewed by Casey Jones, Founder & CEO, Arizona Qualified Applicator, license #31513
Last reviewed:
Short answer
Mostly because mature spiders, especially males, are out looking for mates. As fall temperatures cool, many spiders are near the end of their life cycle and wander, so they turn up in living rooms, garages and bathtubs. Some also slip inside following shelter and insects. Seeing more spiders in fall is a normal seasonal pattern.
Arizona context
Utah State University Extension explains that spider encounters in homes become more common as fall temperatures cool, because spiders near the end of their life cycles are searching for mates. University of Arizona Extension notes that large spiders found wandering into Arizona homes and garages are sometimes fully grown wolf spiders or male tarantulas that have reached maturity. Most of these spiders are harmless. Arizona's two most common venomous spiders are the western black widow and the Arizona recluse.
What you can do
- Seal gaps around doors, windows and utility openings, and add door sweeps.
- Reduce clutter in garages, closets and storage areas.
- Vacuum webs and egg sacs.
- Move woodpiles and stored items away from the house.
- Use less outdoor lighting near doors, since lights draw the insects spiders feed on.
What we see in Safford, Show Low and Sierra Vista
Spiders are the pest Gila Valley customers contact us about most. In the White Mountains, spiders and mice become the top topics in October, as nights turn cold.
When professional service is warranted
Call if you're finding black widows near doors or play areas, seeing large numbers, or want help keeping spiders out year after year.
How Hydra handles it
Hydra inspects for entry points and hiding spots, removes webs, treats targeted areas inside and out, and helps reduce the insects spiders feed on. Ask for a free custom quote.
Frequently asked
Are fall spiders dangerous?
Most aren't. In Arizona, the two most common venomous spiders are the western black widow and the Arizona recluse. If you're bitten, call Poison Control at 1-800-222-1222.
What to do about black widowsDo spiders come inside to get warm?
Some look for shelter as nights cool, but much of the fall increase comes from mature spiders wandering in search of mates.
Will the spiders go away on their own?
Many of the wanderers are near the end of their life cycle, so numbers often drop later in the season. Sealing entry points keeps the next round out.
How can I keep spiders out of my house?
Seal gaps, add door sweeps, cut clutter, vacuum webs and egg sacs, and reduce outdoor lighting near doors.
About the author
Casey Jones is the founder and CEO of Hydra Pest Control, which started with Casey knocking on doors across rural Arizona. Casey is an Arizona Qualified Applicator (license #31513), licensed by the Arizona Department of Agriculture in categories including wood-destroying insects (termites) and ornamental and turf. Casey writes and reviews Hydra's answers using what our Service Pros see in the Gila Valley, White Mountains and Sierra Vista.
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