Yellow Sac Spider

Summary: Yellow sac spiders are probably responsible for more spider bites that occur in the US than any other spider. They have a bite that is painful but does not have long term side effects.

It probably shares more bed space with humans than any other “insect”, with the exception of bed bugs. It's the yellow sac spider which earns its name by building small, tube or sac-like nests.

Pesticides will have little effect on the egg sacs. It's best to simply vacuum these up when you find them. For adult spider control I recommend either a microencapsulated product like  Onslaught insecticide or a flowable powder insecticide like Talstar Pro.

The yellow sac spider is about a quarter-inch long, beige or pale yellow in color, and has two rows of four eyes. It does not have distinguishing markings, but its front legs are longer than the rest of its legs. It is often shipped in agricultural products such as grapes and can make its way into homes on produce. The yellow sac is widely distributed across the country and the world.

This spider is a free ranging hunter, so does not build a web to catch prey. The sac-like silk structure is used only for habitation. It is nocturnal, so it stays in the sac during the day and explores its territory at night using its long front legs at night to search out food...

These spiders usually live outside, but during the fall when temperatures drop and food becomes scarce they come inside in search of food and shelter. The sac spider has a tendency to climb upwards in search of food or as defense mechanism to avoid predators, so the sac spiders commonly build their nests in high places, in the upper corner of a room, behind picture frames on the walls, above window molding, or behind drapes and blinds. People are most often bitten at night while the male spiders are searching for food or a mate.

Sac spiders inject a cytotoxin into their victims which kills cells. The brown recluse spider uses a similar, but more potent cytotoxin, so sac spider bites are sometimes mistaken for brown recluse bites. However, recluse bites take much longer to completely heal, while sac spider bites heal much faster. The bite is described as a sharp stinging pain similar to that of wasp or hornet sting. Sometimes additional symptoms can occur such as a fever, headache, chills, dizziness, nausea, and even shock. If these symptoms occur you should seek medical attention. For any yellow sac spider bite you should clean the area using hydrogen peroxide, followed by an antiseptic to prevent infection. Sometimes skin around the bite will die, but this is not as common with yellow sac spider bites as it is with brown recluse bites. An ice pack applied directly to the bite site will help reduce pain and swelling.

Yellow sac spider eggs

If you see any sac spiders or their sac like nests in the upper corner of a room you can easily vacuum to remove the spider, its nest, and any egg sacs. The egg sacs are small, white and covered in a thin layer of silk. If you do not want to kill the spider you can use a clear jar to capture it. Simply place the jar over the spider and use a note card or other thin, but sturdy barrier to slide under the jar and take the spider outside. If you are transferring the spider using this method, place the jar on the ground and let the spider walk out on its own. Of course, if you are not into saving spiders roll up a newspaper and give it a swat. A perfectly good non-pesticide control method.

To prevent spiders from coming into your home you need to check to make sure all the screens on your windows and doors are secure. Keep firewood and clutter away from the sides of your house and trim tree branches so they don't hang over your roof. Also, take care of any other pest problem such as ants or silverfish that might attract spiders. These pest control methods do not guarantee that spiders will not come into your house, but it is a way not to encourage them to do so.

Spiders are not as dangerous as people thing they are. They rarely attack or bite unless they feel threatened. If you see a lot of spiders around you might want to shake out your clothes and shoes before putting them on and check your sheets before getting in bed. Check to see where they are coming from by setting out sticky traps and trying to locate their food source. Wear gloves when working outdoors handling firewood or moving rocks. Show spiders respect by not picking them up and practice good maintenance of your property by removing spiders and their nests. It might prevent a painful bite or two.

Click here to watch my short video on how to keep spiders in check.