Yellow Sac Spiders

Facts, Identification, & Control

Scientific Name

Cheiracanthium inclusum and Cheiracanthium mildei

Appearance / Identification

What Do They Look Like?

Yellow Sac Spider Illustration
  • Body: The top part of its abdomen includes a dark, lance-shaped mark that runs down the middle of the abdomen from the point where the thorax and abdomen meet to about the mid-point of the abdomen.
  • Color: It has a pale beige to yellow color and often has a tinge of green. Its chelicerae (fangs), and the tips of their legs are dark brown. This leg coloration gives these spiders the appearance of having dark colored feet.
  • Size: The yellow sac spider is a small spider with a body length of about 1/4 inch for both males and females.

How Did I Get Yellow Sac Spiders?

Like most other types of spiders, these pests don’t necessarily want to live near people. Yellow sac spiders may wander inside through an open door or follow infestations of prey insects that may wander inside a home.

Fall is the most common time to notice them indoors, as they may also come into houses seeking shelter from the cold. In the summer, yellow sac spiders usually live in gardens and under debris located on the ground.

How Serious Are Yellow Sac Spiders?

Yellow sac spiders are nighttime hunters that search for prey rather than catching their prey within a web. Therefore, these spiders may come into contact with people if they should be trapped between a person’s skin and bed sheets, clothing, or shoes. They may also bite if a person provokes the spider while gardening or working in a location of preferred habitat.

Bites from a yellow sac spider can be painful and mildly necrotic, meaning that the venom will damage and kill skin tissue. People often misdiagnose these wounds as brown recluse bites, even though they are much less severe. Reactions to a bite may include a slow-healing sore, itchiness, and swelling. These bites are not considered to be extreme, medically important venomous biters and are usually not a cause for concern.

Signs of Infestation

The appearance of either immature or mature spiders and their protective sacs are signs of a yellow sac spider problem.

How Do I Get Rid of Yellow Sac Spiders?

What You Can Do
Yellow sac spider prevention is best accomplished by sealing holes, cracks, and gaps in the home’s doors, windows, and foundation that enable the spiders to enter the home. Removing inside clutter that serves as harborage for spiders is also helpful.

What Orkin Does
Your local Orkin technician is trained to help manage yellow sac spiders and similar pests. Since every building or home is different, your Orkin technician will design a unique program for your situation.

Orkin can provide the right solution to keep yellow sac spiders in their place…out of your home, or business.


Behavior, Diet, & Habit

What Do They Eat?
Yellow sac spiders usually feed on other spiders, plus agricultural and garden pest insects and their eggs. If food sources are limited, these spiders become cannibalistic and may consume their own eggs.

Where Do They Live?
Yellow sac spiders are usually most active at night, and during the day will retreat to their web masses (sacs) for protection against predators. Outdoors, these spiders normally are found hiding in rolled up leaves or in other debris in small, hidden locations. In addition to protection, these daytime hiding places also function as molting sites (shedding of their outer “skin” in order to grow larger), mating, egg laying, and hibernating sites. Their preferred habitats around the home are in:

  • Bushes
  • Gardens
  • Leaf piles
  • Trees
  • Woodpiles

Geographic Range
Yellow sac spiders are found throughout most all of the United States, but are fewer in number within the northern, colder climates.

Reproduction
Male yellow sac spiders will hunt for females and breed with them in the early summer. Females typically mate only once but produce as many as five egg sacs, each of which contains approximately 40 eggs. Their egg sac serves to protect not only the mature spiders, but also to protect the eggs and immature stages of the yellow sac spider.