Yellow sac spiders (Cheiracanthium)

Yellow sac spiders are one of the more commonly encountered indoor spiders across North America. Often confused with other pale spiders, these small arthropods are known for their hidden silk sacs and painful bites. Commonly found outdoors during the warmer months, they move indoors seeking shelter and prey when the weather cools.

What are yellow sac spiders?

Yellow sac spiders belong to the Cheiracanthium genus and are often referred to as the yellow house spider due to their coloring and tendency to appear indoors. Though small, they are active hunters that don’t rely on webs to catch insects. Instead, they hide during the day in silk sacs and emerge at night to look for food. These spiders are often mistaken for other pale spider species, but can be identified by their coloring, body shape, and hiding habits. 

While yellow sac spider bites aren’t usually dangerous to most people, they are sharp and painful and can cause erythema (redness of the skin) and swelling. A wheal may develop, producing a necrotic area (dead tissue) that can take eight weeks to heal. Pain or numbness at the site of the bite may be followed by sweating and nausea lasting for up to 24 hours.

The lifecycle of yellow sac spiders

The lifecycle of a yellow sac spider gives insight into when they’re most active and why they move indoors. From laying egg sacs in the fall to spiderlings hatching the following spring, these spiders follow a clear seasonal pattern. Reproduction also includes a surprising fact—males may not survive the mating process.

• A female produces around five egg sacs, each with 30 to 48 eggs. The female may produce several egg masses during her lifetime.
• Eggs are laid in autumn.
• Spiderlings emerge the following spring.
• Approximately 30% of adult males get eaten by females after mating.

Seasonal behaviors of yellow sac spiders

You’re more likely to see yellow sac spiders indoors from early fall. As temperatures drop and outdoor insect prey becomes scarce, they enter buildings looking for food and warmth. During the day, they hide in their silk sacs, often built in quiet corners of homes. At night, they actively roam in search of prey.

Spider activity typically increases in fall, but adult spiders can most commonly be seen from April through November. Their movement indoors usually signals a drop in outdoor food sources.

Habitat and diet of yellow sac spiders

Where you find yellow sac spiders often depends on the time of year and food availability. These spiders prefer quiet, protected areas and hunt rather than spin webs. Their diet mainly consists of insects, which makes them more likely to move indoors when prey becomes harder to find outside.

Preferred environments of Cheiracanthium

Yellow sac spiders prefer quiet, undisturbed places where they can hide during the day. Outdoors, they often settle under logs, inside curled leaves, or tucked into bark. Indoors, they build silk sacs in high corners, behind furniture, inside closets, or at the junction of walls and ceilings.

These spiders don’t spin webs to catch prey. Instead, they create silken tubes as daytime retreats and emerge at night to hunt. While they are usually outdoor spiders, they’ll set up indoors if there are small insects available.

What do yellow sac spiders eat?

Yellow sac spiders are hunters. Their diet mostly consists of insects, such as flies, ants, and small moths. They don’t trap their prey in webs—instead, they roam at night and catch their food directly.

If you’re seeing these spiders around your home, it might be a sign that other pests are present. That’s why it’s important to manage not just the spiders, but their food sources too.

Managing yellow sac spiders

Spotting a yellow sac tucked in the corner of your ceiling or finding a spider crawling across the wall at night can be unsettling. And having them around might mean there’s another pest problem.

Preventing yellow sac spider infestations

To keep these spiders out of your home, seal gaps and cracks in walls, around windows, and doors. Clear out clutter, especially in places like basements and attics. Also, reduce outdoor lighting because it draws insects. Limiting their access to food sources like small arthropods and other household insects is key; keeping your property clean and tidy helps cut off their food supply.

Effective yellow sac spider control methods

The most effective way to control yellow sac spiders is to tackle both the spiders themselves and what’s attracting them—usually other pests. Vacuuming up visible spiders and egg sacs can help reduce their numbers in the short term.

However, DIY methods are often only a temporary fix. For long-term protection and to make sure the root cause of the problem is addressed, it’s best to call the professionals at Presto-X. Our yellow sac spider control service is designed to help reduce current activity and help stop future infestations.

Frequently asked questions