Sac Spider


Actual Size: ¼ to ⅜”

Characteristics: Yellow abdomen with tan legs and head.

Legs: 8

Habitat: Typically remains outdoors in gardens or organic debris, but may seek warmth and shelter indoors during cold weather. Often builds webs in corners and ceilings.


  • Builds small tube or sac-like nests, hence their name.
  • Looks similar to the brown recluse spider, but lacks the fiddle shape on its back.
  • Though their bite can swell and be painful, it is not medically significant unless there is an allergic reaction.

Sac Spiders in the Pacific Northwest

Sac spiders – sometimes called “yellow sac spiders” – get their name from the unique sac-shaped webs they spin. These spiders are pale yellow in color, though some have been known to have a tinge of green as well. Due to their shape and color, sac spiders are often mistaken for brown recluses. However, sac spiders do not have the telltale “fiddle” or violin-shaped pattern on their back. Sac spiders are antisocial and usually stay outdoors away from humans, but they can be carried indoors on accident or may seek shelter in homes when temperatures drop.

Sac Spider Habitat

Sac spiders typically prefer to remain outdoors, except in the winter months. These spiders are attracted to dark and damp areas, so some common hiding places include under vegetation, in rolled leaves, and beneath organic debris. Though these spiders primarily live outdoors, they are also frequently shipped in agricultural products such as grapes and can make their way into homes on produce. Once indoors, they often build their sac-like webs in the corners of walls and ceilings.

Sac Spider Behaviors, Threats, or Dangers

Though sac spiders generally try to stay away from humans, they may bite if they feel threatened – such as if they are pinched, squeezed, or crushed. Their bites are painful and often misdiagnosed as brown recluse spider bites. Though unpleasant, these bites are not medically significant unless an allergic reaction develops. Swelling, slow healing, and ulcerated sores on the bite may are signs that medical attention may be necessary. If you have sac spiders in or around your home, it is a good idea to contact your local spider exterminators to remove them quickly.