Sac Spiders are usually about 1/4th to 3/8th inch in size. They make silken retreats inside curled up leaves or between two layers of fabric. There are several different sac spiders present, from yellow to dark cinnamon to tan. Yellow Sac moved into the area from Europe and can be the most common spider found in homes in Washington. It has a banana yellow abdomen with a dusky yellow cephalothorax with no conspicuous markings. This Spider does bite man aggressively, and the bite is like a bee sting, causing redness and pain, the typical response is mild redness, itching, and slight swelling over a few days.
Sac Spider Habits
Even though spiders are beneficial due to their role as predators of insects and other arthropods, they still are a common Northwest pest as many people fear or dislike spiders because of their looks, speed of travel and sometimes reactive bites. Most spider bites occur as a reaction or for protection at night when spiders are more likely to move about in our structures and when we may roll over them during our sleep or sit on one in a piece of furniture. This can be a disconcerting thought which is why many people like to control their populations inside while allowing them to perform their role of insect population control on the outside.
Biology of Spiders
Spiders resemble insects and sometimes are confused with them, but they are arachnids, not insects. Spiders have eight legs and two body parts: a head region (cephalothorax) and an abdomen. They lack wings and antennae. Although spiders often are found on plants, they eat mainly insects, other spiders, and related arthropods, not plants. Most spiders have toxic venom, which they use to kill their prey. However, only those spiders whose venom typically causes a serious reaction in humans are called “poisonous” spiders.
