What You Need to Know About Yellow Sac Spiders

What You Need to Know about Yellow Sac Spiders
Picture of Israel Alvarez
Israel Alvarez

Owner @ Insight Pest Management

Table of Contents

While spiders can help control other potential pests found in the home, most homeowners still prefer to keep these pests at bay. In most cases, these household pests do not pose a danger to humans. However, the yellow sac spider is one of the most common spider species found in California that can pose a potential threat. In fact, bites from the yellow sac spider are often mistaken for a bite from a better-known venomous spider, the brown recluse spider.

Here we take a closer look at the yellow sac spider, how to identify them, and how to keep them from sharing your personal space.

Key takeaways

  • Learn how to identify the yellow sac spider.
  • Understand the potential risks associated with these spiders.
  • Explore ways to eliminate these spiders from your home.

What are yellow sac spiders?

There are two species of yellow sac spiders commonly found in California. The first one, Cheiracanthium inclusum (C. inclusum) is native to our state and is commonly found outside in landscaped areas. The second, Cheiracanthium mildei (C. mildei), was introduced to North America in the 1940s from Europe and is most often found inside homes.

Physical appearance

Both species of yellow sac spiders are between ¼ – ½ inch long and, despite their name, can be light yellow, white, or greenish in color. Their legs and cephalothorax are usually darker in color than their abdomen. Their shape is similar to that of the brown recluse, though they do not have the characteristic “fiddle” shape on the abdomen as the brown recluse does.

Life cycle

After mating, female sac spiders lay around 30 to 48 eggs are a time, typically in the fall. These eggs are often separated into as many as five different sacs covered in a thin coat of spun silk. The female spider guards the egg sacs until they hatch, and the spiderlings emerge in the spring. Adult yellow sac spiders can live up to two years.


Yellow sac spiders can be found both indoors and outdoors. Outside, you will find these spiders under vegetation, in bark, and around any areas of yard debris. They often hitch a ride in produce, such as grapes. They create silk tube-like sacs that they hide in throughout the day. Inside, you can find these tube-like sacs in the upper corner of walls, window sills, and around picture frames.


The yellow sac spider is a species known for daytime rest in the tube-like sacs they spin. Once the sun goes down, these spiders become fierce hunters looking for smaller insects and spiders to feed on.

Are yellow sac spiders poisonous?

Yellow sac spiders are not known to be aggressive spiders that bite humans. However, because they hunt at night, they are very likely to come into contact with humans lying in bed. If the spider becomes trapped, such as when you roll over or between your skin and clothing, the spider can bite. While the spider venom from the yellow sac spider produces minimal effects, there are rare cases when the bites can cause a severe reaction and even a necrotic lesion at the site. If you suspect a spider bite, it is always a good idea to seek medical attention.

Bite symptoms

In most cases, a bite from a yellow sac spider will not do much more than create a small red welt. While many describe the bite as painful and similar to a wasp sting, others report no sense of discomfort at all. In some cases, however, the bite can cause blisters and skin necrosis that worsens if the bite becomes infected. Other symptoms that can occur with a yellow sac spider bite are nausea, headaches, dizziness, and a fever. Similar to bee stings, people can also be allergic to the venom of the yellow sac spider, resulting in potential anaphylactic shock and severe symptoms.

How to manage and get rid of yellow sac spiders

If you have a large yellow sac spider population in and around your home, professional spider control is recommended in order to eliminate the population. However, there are things you can do the help deter these spiders from taking over your garden and entering your home.

Outside home

It is important to address any areas these spiders may be attracted to. This includes areas of lawn clutter, wood piles, and vegetation overgrowth. In addition, look for places where they can hide under. These spiders are nocturnal hunters and spend their nights looking for food. Regular pest management will help keep food sources away and leave them looking for other places to call home.

Inside home

It is important to keep other pests at a minimum in order to eliminate the yellow sac spider’s food source. If there is nothing available to eat, they will move on. During the day, these spiders look for places to build their tube sacs and hide. While this can be in doorways or windows inside the home, it can also be inside shoes or clothing left on the floor. In fact, spiders hiding in these places are often the common source of accidental bites. Before putting your shoes on or grabbing a shirt to put on, it is a good idea to give them a shake and make sure you don’t have any spiders hiding within. Don’t forget your bed either. Before crawling in for the night, pull back and check your sheets for spiders.

No one wants to share their home with spiders

While Charlotte and her web messages may have been a favorite when you were a child, most homeowners strive to keep webs and spiders at bay. While the yellow sac spiders do not usually pose a serious threat, their bite is something you probably want to avoid. By keeping your yard free from clutter and having a professional pest control and management plan in place, you will likely keep these spiders from overtaking your home.

Keep your home spider-free

When spiders take over your home or yard, trying to eliminate them can become frustrating. At Insight Pest Management, our team understands spider behavior and how to best ensure your home and garden remain spider-free. To learn more about how we can help, contact us today for a free evaluation.

Serving all of Ventura County

Locally owned and family operated, we are a top-rated pest and bug control company that uses state-of-the-art equipment to help ensure that pests are located and eliminated. But it doesn’t stop there! Pest prevention is one of the most important parts of pest and bug control. 

Our expert technicians work to ensure that all potential pest entry points are sealed and offer routine treatment options to help ensure your home or business stays protected from future infestations. You don’t have to share your home or business with pests any longer! If you live in the Ventura County area, let the team at Insight Pest Management help you say goodbye to pests once and for all!

Contact us today to schedule a FREE evaluation!

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