The Yellow Sac Spider

The yellow sac spider, with the Latin name Cheiracanthium inclusum is very common in most of the United States. The yellow sac spider is a cause of many bites in the U.S., and a lot of house spiders are crushed on suspicion of being yellow sac spiders. Its bite correspond in pain to a bite from a wasp.

Are yellow sac spiders poisonous?

Yes yellow sac spiders are venomous - poisonous in daily language.

Bites from yellow sac spiders are also often misidentified as brown recluse spider bites. The symptoms and the development of the wound are quite the same but much less severe.

Life Cycle of the Yellow Sac Spider

In the autumn, when the food is disappearing, the yellow sac spider heads indoors to find food. It is often seen on walls. If disturbed, it drops to the floor.

Egg sacs are laid in corners of all sorts. The egg sacs are white and spun with silk. The female may guard its egg sac, so one has to be careful removing egg sacs from a yellow sac spider.

During the summer, when there's plenty of food, the yellow sack spider prefers to live on trees, shrubs, and in low vegetation close to open expanses, such as fields. Occasionally it is found in cotton crops.

A yellow sac spider on a green leaf


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The yellow sac spider over winters as spiderlings (juveniles) and molts to the adult stage during spring. Females of the yellow sac spider cover her loosely distributed eggs with thin white silk. Adults can be found from April through November, but in the hottest months, small spiders make up the largest proportion of the population.

How and When Yellow Sac Spiders Search for Prey

Yellow sac spiders are active in the night, where they wander around to find prey. Their prey is a wide diet of arthropods, including spiders larger than themselves and even their own eggs.

The spider does not produce webs. Instead, they construct sacs in protected areas. The idea of creating sacs instead of webs gives the yellow sac spider its name.

Around 30 percent of adult males are killed and consumed by females at mating. A female produces around five egg sacs each, with around 37 eggs in each sac. Their eggs are laid in a loose mass and covered with a thin coat of spun silk.

The Strength of the Fangs of a Yellow Sac Spider

The chelicerae of yellow silk spiders are very powerful, and the fangs can penetrate human skin quite easily. Most bites on humans occur when people are gardening or performing other kinds of outdoor activities. The venom has mild and local cytotoxic and neurotoxic effects. No fatal incidents from encounters with the yellow sac spider have ever been recorded.

However, the bite is quite painful from the outset. A person usually develops redness, swelling, and itching near the site of the bite. Redness disappears after about 72 hours, and the skin heals in a week or two.

Sac spiders are the probable cause of more spider bites than any other kind of spider, and their bites are often misdiagnosed as brown recluse bites by health care providers.

Preventing Spider Bites

If you want to prevent you and your family from yellow sac spider bites, you can take certain precautions. First of all, you can shake your clothes before getting dressed. Also, you can wear pre-inspected clothes when doing garden work or handling firewood, etc. Bymoving your bed away from the wall, you can minimize the risk of close encounters with the yellow sac spider while asleep.

To protect your house from yellow sac spiders, you can install tight fitting screens on windows and doors. You can also seal any crack or crevice a spider can fit into or get access to your house through. Installing yellow light on your front and back porch might also attract fewer insects, which are food for most, if not all, spiders.

If you want to go further, you can remove any kind of debris near the foundation of your house. You can make a tight cleaning schedule in your house or apartment to get rid of insects, etc., that will attract spiders (which, by the way, are not insects) because insects are prey.

Other Sites About the Yellow Sac Spider and Other Spiders

These are some good quality sites about the yellow sac spider and the brown recluse spider.


Ohio State University

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