Yellow sac spiders, common in homes and outdoors, often raise questions about their movement, especially if they can jump. They do not jump. Instead, they primarily walk or scurry rapidly. If startled, a yellow sac spider may quickly drop on a silk line, a maneuver sometimes mistaken for jumping.
How Yellow Sac Spiders Move
Yellow sac spiders are active, nocturnal hunters that do not construct webs to capture prey. During the day, they retreat into small, silken sacs that serve as shelters. They spin these sacs quickly, often in secluded spots like wall-ceiling junctions or behind furniture.
At night, yellow sac spiders emerge from their sacs to search for insects and other small arthropods. Their locomotion involves swift walking and running as they pursue prey across various surfaces. While they do not jump, they use silk as a dragline, allowing them to drop rapidly if threatened. This quick descent on a silk thread, combined with their fast scurrying, can create the impression of a jump.
Identifying Yellow Sac Spiders
Yellow sac spiders are relatively small, with a body length typically ranging from 1/4 to 3/8 of an inch (5 to 10 millimeters). Their coloration can vary from pale yellow to light green or cream, sometimes exhibiting a slightly shiny appearance. Some species may also have a faint, darker stripe running lengthwise along the top of their abdomen.
These spiders have long, slender legs, with the front pair being noticeably longer than the others. They have eight eyes arranged in two horizontal rows. Their distinctive silken sac is a small, tube-like retreat, not a web for catching prey. These sacs are often found in corners of rooms, along ceilings, or in other undisturbed areas.
Yellow Sac Spider Bites
Yellow sac spiders are venomous, but their bites are generally not considered medically significant for most individuals. A bite typically causes immediate, sharp pain, followed by redness, swelling, and a burning sensation. Sometimes, a small lesion, blister, or rash may develop.
Rarely, some individuals might experience mild general symptoms like headache, nausea, or muscle cramps. Clean the bite area with soap and water and apply a cold compress to reduce swelling and discomfort. Seek medical attention if symptoms worsen, signs of infection appear, or an allergic reaction is suspected. Bites often occur when the spider is accidentally trapped against skin, such as in clothing or bedding.