Yellow sac spiders – also called Cheiracanthium – are typically pale in color, and have an abdomen that may range from a slightly greenish yellow to beige.
They have a lance-shaped mark from their waists (where their abdomen meets their cephalothorax) that runs down mid-point of the abdomen, and they have dark-colored fangs and feet (because of this, they’re also sometimes called the “Black-Footed Spider”).
Their chelicerae, or fangs, point diagonally forward and cross in a pinching action, as opposed to fangs pointing straight down that you may find in other spiders.
They have eight dark eyes sized similarly and arranged in two horizontal rows.
They’re small spiders at only about a quarter of an inch for both males and females, with males being more slender and with a slightly longer leg span of up to an inch. The front legs are the longest.
Yellow sac spiders don’t build your typical spider web and instead construct sac-like web structures often found in protected areas such as within leaves, under logs or at the junctions between walls and ceilings (they’re often found inside homes, and one species of yellow sac spider is a common house spider).
These nest sites are also where they molt, mate, lay eggs, and hibernate.
BEHAVIOR AND DIET:
They’re nocturnal spiders and only hunt at night. They don’t have spider webs where they wait for prey to catch, and instead actively hunt their prey.
While they actively hunt arthropods, even spiders larger than themselves, they are not particular about what they eat and will hunt just about any small insect. They also eat insect eggs, If they fail to find other food sources, they can also turn cannibalistic and consume their own eggs.
HOW DANGEROUS ARE THEY?
Even though they’re quite small, their fangs can easily penetrate human skin and their bites are mildly venomous to humans.
There are many species of yellow sac spider, and they all have venom with necrotic properties (though none are as potent as the infamous brown recluse spider). Their bite can be quite painful, and cause swelling and lesions. Other reactions may be slow-healing sores and itchiness (it may be interesting to note that a lot of reported Brown Recluse spider bites may actually be from yellow sac spiders, since the symptoms are much less severe).
The good news is that there are no reported fatalities from yellow sac spider bites.
WHEN ARE THEY MOST ACTIVE:
Male yellow sac spiders will look for females to breed with during the early summer. They only mate once but produce as many as five egg sacs, each sac containing approximately 40 eggs.
HOW DO YOU GET RID OF THEM?
Seal or caulk cracks along your walls.
Use weather stripping on doors and windows.
Use nets on windows, and any outside vents.
Remove clutter that may serve as harborage for spiders.
Keep your home clean and insect free to minimize their food source.
If you think you have a spider infestation in your home, get in touch with your local pest control company right away!