Moisture, mold & pests

Spiders in the basement

Basements are a common spider habitat because of the dark, undisturbed, and often damp conditions, and most house spiders are harmless even though they can look alarming.

Difficulty
Easy
Time
1–2 hours
DIY cost
$10–$25
Pro cost
$100–$300

Symptoms

  • Webs in corners, near windows, or between stored items
  • Spiders seen scurrying when boxes or storage areas are disturbed
  • Occasional larger spiders that look intimidating but are usually harmless

Likely causes

  • CommonDark, undisturbed clutter providing shelterBasements often have boxes, furniture, and storage that spiders use for cover.
  • CommonInsect prey attracted to the basementSpiders follow their food source; a basement with other bugs will likely have more spiders too.
  • PossibleDamp conditions favoring certain spider speciesSome spiders, and their insect prey, prefer higher humidity environments like basements.

What to do

  1. Vacuum up webs, egg sacs, and visible spiders regularly, focusing on corners, window wells, and storage areas.
  2. Reduce clutter and elevate stored items off the floor to remove hiding spots.
  3. Address any dampness or high humidity in the basement, since reducing other insects (spider prey) also reduces spiders.
  4. Seal exterior gaps around windows, the foundation, and utility penetrations to limit new spiders (and their prey) from entering.
  5. Use sticky traps along baseboards to monitor and catch spiders without chemicals.
  6. Learn to recognize a couple of medically significant spiders relevant to your region, like the black widow or brown recluse, and take extra caution around dark corners if those are present locally.
  7. Call a pest control professional if you find a spider you can't identify and suspect is dangerous, or if the basement has an unusually high spider population.

Tools and parts

  • Vacuum
  • Broom
Spider sticky trapsSearch: “spider glue traps”

When to call a pro

Call a pest control professional for large populations, a suspected venomous species, or persistent spider activity after cleaning.

Safety

Use caution

If you suspect a black widow, brown recluse, or other venomous spider in your region, avoid handling it directly and use a trap or call a professional instead.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.