Light yellow to pale yellowish green, sometimes with a orange-brown stripe on top of the abdomen. An adult female sac spider's body typically is 1/4- to 3/8-inch long, and her leg span is up to 1 inch. Males are more slender, with a slightly larger leg span. The first pair of legs is longer than the fourth.
Yellow sac spiders are generally outdoor spiders, preferring foliage to structure, at least in warmer climates or seasons. But sac spiders are hunters, and they will search for prey indoors when there is little to be found outside. Thus, in the fall, they may move inside dwellings if they can find a food source therein.
Yellow sac spiders are venomous. The effects of their bites resemble those of the brown recluse and hobo spiders, although not nearly as severe. Plus, they heal more rapidly. The harm, however, is localized. The bite itself may feel similar to a bee sting. It will likely redden and get itchy, and it may result in a blister. On rare occasions, a small necrotic lesion may form. Systemic effects are usually not severe, but when they occur may include chills, fever, headache, dizziness, nausea, anorexia, and sometimes shock.