A Yellow Sac Spider is a beneficial species of sac spider native to the United States, where it is found primarily in the northeastern to midwestern states.

Similar species to the American version are found in many countries across the world including Germany and Australia. These spiders are active hunters who do not wait in a web for prey to come to them, but rather go out in search of food. They are nocturnal, so they do build small “sac” webs or nests during the day, in which to rest.

There is some fear of these spiders because Yellow Sacs have been known to bite humans, however, there is little cause for alarm when encountering or even being bitten by a Yellow Sac Spider. Though they are somewhat venomous, mildly aggressive when provoked, and their bite can in extremely rare cases create necrotic tissue, Yellow Sac Spider venom is nowhere near as potent as that of a Brown Recluse and is not remotely potent enough to be fatal to humans. There is actually only one documented case of a Yellow Sac bite causing necrotic tissue.

4 Incredible Yellow Sac Spider Facts!

• Yellow Sac Spiders are primarily nocturnal.
• Yellow Sacs do not catch prey in a web, but are instead active hunters.
• They only use their web for resting during the day.
• They are mildly venomous, but their bites are not deadly.

Yellow Sac Spider Species, Types, and Scientific Name

There are two species of Yellow Sac Spider in the United States. Cheiracanthium inclusum is the scientific name for the most common species of Yellow Sac Spider, though this was not always the case. Originally, they were placed in the Clubionidae family, and then later the Miturgidae family, before finally being labeled as Cheiracanthiidae. C. mildei is the other species found in the U.S. and C. punctorium is the species of Yellow Sac found in Europe.

Appearance: How To Identify Yellow Sac Spiders

The color of these spiders varies so much that it is not a good indicator of whether you have found a Yellow Sac Spider. For that, you will need to rely on other features. To begin with, a Yellow Sac’s legs are significantly longer than its quarter-inch body. The front two legs will be longer than the other six legs. They are typically very pale, sometimes even bordering on translucent, and the tips of their legs are much darker than the rest of their legs.

They will most likely not be found in their web, but if they are, the web will be very small and tunnel or sac-shaped. They have two rows of eyes, with four symmetrical eyes on each row. They tend to have a stripe from the middle of their body to the back, but this can be hard to see on some colorations. They will most often be seen at night.

Habitat: Where to Find Yellow Sac Spiders

Yellow Sac Spiders can be found in the woods, and also in homes and gardens. These spiders are hunters, but they tend to stick within a few yards of their resting webs. They like to make these under woodpiles and yard debris, behind clutter, and around baseboards. Inside the home, they like dark, damp places with lots of places to hide and prey to hunt.

Diet: What Do Yellow Sac Spiders Eat?

Yellow Sac Spiders are carnivores, though they will occasionally drink nectar. They enjoy hunting insects that we normally consider pests, including cockroaches and insect eggs. They will also eat other smaller spiders and, when resources are limited, will even consume their own egg sacs.

Prevention: How to Get Rid of Yellow Sac Spider

• Positively identify the Yellow Sac Spider using the tips listed above. Do not get close enough to allow the spider to bite you because they are aggressive when bothered.
• Inspect the property, paying attention to gardens, wood piles, basements and closets, to determine if there are multiple spiders in or near the home. Look for tunnel webs containing egg sacs.
• While wearing protective gear like gloves, mask and long sleeves, remove any debris or clutter where spiders were found. Remove any children or pets from the home or move them to a safe room, away from the treatment area. Apply Bifenthrin-based insecticide treatments to gardens, foundations, baseboards and other areas where the spiders were located. For heavier infestations, put down glue traps to monitor for further activity.
• Prevention reinfestation by repairing torn window screens, sealing cracks and holes and decluttering the home, to reduce the chances they can reenter the home and to remove attractive places for them to seek shelter.

Yellow Sac Spider Bites: What You Can Expect

A bite from a Yellow Sac Spider will most likely be red and swollen. Sometimes it is possible to see fang marks, but this is not common. As previously stated, Yellow Sac Spider bites are not deadly. If you are bitten, the bite may be quite painful for 90 minutes or so. After that, the most common symptoms will be redness, itchiness, and swelling. In some rare instances, the person may feel nauseated. There has only been one documented case of such a bite developing an ulcer, also known as necrotic tissue.

The most important thing to do if bitten by a Yellow Sac, as with any wound, is to keep the bite area clean and dry, perhaps with some over-the-counter antibiotic ointment and a bandage, to reduce the risk of infection. Recovery usually happens within just a few hours. If symptoms persist much longer than that, get worse, or in the unlikely event that the bitten person shows any signs of anaphylactic shock, seek medical attention immediately.

The easiest thing to do, if you live in an area where Yellow Sac Spiders are common, is to avoid a bite altogether. To do this, always wear gloves when gardening or picking up firewood or lawn debris, particularly in colder months. Shake out any clothing in closets that haven’t been worn in a long time. Keep your home as clutter-free as possible.

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