Yellow Sac Spider

The Yellow Sac Spider

Yellow Sac Spider

Yellow Sac Spider by Vengolis – Own work, CC BY-SA 4.0 

The Yellow Sac Spider (scientific name- Cheiracanthium inclusum and Cheiracanthium mildei) is those house spiders which instead of making a web, usually prefer constructing sacs in protected areas – hence the name yellow “sac” spiders. These spiders are very common in the United States and decrease in numbers as we move towards the cold, northern regions. Often confused with brown recluse spider bites, their bites sting as much as that of wasps but are much less severe than either of them.


If the spiders you are seeing in your house have the following features, you can be sure that they are the yellow sac spider:

  • Pale beige to yellow in color
  • May have a tinge of green as well, with fangs and tips of legs dark brown in color
  • Dark, lance-shaped mark covers major part of it abdomen (top view)
  • Length differs from 5mm to 10mm for both, males and females

Appearance, Behavior, and Signs

  • Usually avoiding human contact, but in case they sense danger, they are quick to jump from the walls to the ground and scatter
  • Most active at night time, these spiders hunt for their prey instead of waiting near their sacs
  • At daytime, they prefer to stay in their constructed sacs and use this place for: molting (shedding their outer skin so as to grow larger in size), mating, laying eggs, and hibernating (sometimes in winters)
  • During summers, they can be generally found on trees, shrubs, and in agricultural lands. Occasionally, cotton crops too. Their eggs generally hatch in winters, wherein they start their transitioning phase till spring season
  • Breeding usually takes place during summer season, with males hunting for females to mate with. Females mate less but produce as much as five sacs with approximately 40 eggs in each one of them
  • The sacs which are constructed are not only for protecting the eggs but also immature (phase) and mature spiders
  • The possible chances of a human being bit by such spiders is if they are trapped between a person’s skin and bed sheets, clothing, shoes or in gardens/ fields
  • Their bites can be painful and may damage tissues on the area infected. Their bites may result into soreness, itching and swelling and it generally takes 2-3 weeks to heal completely. However, these are definitely not something to sweat about since they cause no further damage


  • They normally live in closed and/or cornered spaces for example, in rolled up leaves or a pile of clothes thrown in a corner.
  • In autumns, with a decrease in food resources, these spiders move indoors and can be found on walls.


  • Precautions: Shake clothes before getting dressed, place your bed away from the wall as much as possible, and while gardening makes sure to shake the grass with a stick so that they are warned and can scurry away before you step your foot in an area.
  • Prevention: Sealing holes, cracks, gaps at home, and tightly sealing windows with a net surface (too small gaps for spiders to cross).
  • Cure: In the case that they have already entered the household premises, the one way to get rid of them is cleaning all surfaces and corners. Also, one may install a yellow light at the entrance and/or exit of your house, which would attract insects from outside and thus, lead the spiders towards their food. Your can also try spider traps found on Amazon.

Yellow Sac Spider Facts

  • These spiders usually feed on other spiders (even bigger than them in size) and/or insects. However, the lack of food can lead them to turn cannibalistic in nature and feed on their own eggs.
  • Females sometimes kill and consume the males they mate with during the breeding season.
  • Majority of house spiders are smashed because of yellow sac spiders. Once bitten by them, people generally go into attack mode against every other spider in their premise.