The Yellow Sac Spider (Cheiracanthium) is likely the most common spider you’ll see inside a Utah home. Unlike many of their outdoor cousins, these spiders thrive in the temperature-controlled environment of our living rooms and bedrooms.
Yellow Sac spiders are often misidentified because of their plain appearance, but they have several distinct markers:
The ColorThey are typically a pale yellow, beige, or light "citrine" green. Their legs are often slightly darker than their bodies.
The "Feet"If you look closely, their "feet" (tarsi) appear black or dark brown, making it look like they are wearing tiny socks.
The SacYou will rarely see them in a traditional web. Instead, they build small, white, silk "sleeping bags" or tubes, usually in the corners of ceilings or behind picture frames.
While Black Widows wait for food to come to them, Yellow Sac spiders go out and find it.
Ceiling RoamersThey are expert climbers. During the day, they hide in their silk sacs. At night, they emerge to hunt across walls and ceilings, which is why homeowners often spot them in the "middle" of a white wall.
Indoor ResidentsThese spiders are well-adapted to indoor life. They don't need a garden to survive and can often be found in Utah homes year-round.
AggressionThey are known to be slightly more "nippy" than other spiders. Most bites occur at night when a person accidentally rolls over on a spider that has wandered into bedding.
Is the bite dangerous?The bite is painful—often compared to a bee or wasp sting—and can cause localized swelling and itching. While it was once thought to be necrotic, science has shown it does not cause skin rot.
Why do I keep finding them in my bed?Because they are active hunters, they roam far from their hiding spots. They often drop from the ceiling or climb up bedskirts while searching for small insects.
How do I get rid of the white sacs?The sacs can be easily vacuumed or wiped away. However, if the sacs keep reappearing, it means the spiders are successfully breeding inside the home.
