Identification
Yellow sac spiders are small, measuring about 1/4 to 3/8 inch in length. They have a pale yellow to light green body with darker mouthparts. Their legs are long and slender, and they have eight eyes arranged in two rows. Unlike some spiders, they do not spin traditional webs but create small silk sacs for shelter.
Lifecycle & Reproduction
Yellow sac spiders undergo incomplete metamorphosis, progressing from egg to spiderling to adult. Females lay about 30 to 50 eggs in silk sacs, which hatch in about two weeks. Spiderlings mature within a few months, and adults can live for up to a year. They are active year-round but more common indoors during colder months.
Habits, Diet & Behavior
Yellow sac spiders are nocturnal hunters, preying on small insects and other arthropods. They do not rely on webs to capture food but actively hunt their prey. They are known for their fast movements and can be aggressive if disturbed.
Where You’ll Find Them / Typical Locations
Yellow sac spiders prefer undisturbed areas and are commonly found:
- Inside homes, near ceilings, corners, and wall crevices
- Under leaves, logs, and garden debris outdoors
- Behind furniture and stored items
- Inside clothing, shoes, and bedding
- Around windows and door frames
Threats & Danger
Yellow sac spiders can bite humans if provoked. Their bites are painful and may cause redness, swelling, and mild necrosis in rare cases. While their venom is not medically significant, reactions can vary based on individual sensitivity.
Prevention
- Seal cracks and gaps around windows, doors, and foundations
- Reduce clutter and stored items where spiders can hide
- Regularly clean corners, ceilings, and behind furniture
- Shake out clothing and bedding before use
- Use yellow outdoor lighting to reduce insect attraction
Signs of Infestation
- Small silk sacs in corners of walls and ceilings
- Presence of yellowish spiders crawling on walls at night
- Unexplained bites with mild swelling or irritation
- Increased spider activity during cooler months
- Egg sacs hidden in protected areas
How to Get Rid of It
- Use residual insecticides around baseboards, ceilings, and windows
- Vacuum and remove webs, sacs, and spiders regularly
- Apply diatomaceous earth or natural repellents in hiding spots
- Use sticky traps to monitor and capture spiders
- Contact professional pest control for persistent infestations