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.
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
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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.
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here to watch my short video on how to keep spiders in check.
Comments
Upstairs Chris
24 May 2009, 05:56
I've been seeing this spider crawl up my living room walls 4 nights in a
row now and I've killed it each time. I am I supposed to believe there is a
nest or something? I finally caught one tonight and all signs point to the
sac spider. I guess I am kinda relieved, I thought they were brown
recluse's. How many usually live together? I am getting pretty proficient
at killing them and they come out like clockwork.
You're article was very helpful too.
Ask the Exterminator
24 May 2009, 08:56
The female lays from 30 to 45 eggs. Either you locate the nest or you'll be
killing spiders for the next month or so.
Karolis C
31 May 2009, 04:55
Yellow Sac Spider bite, One summer day i was working for a painter and I
was taping up over hangs for spray painting and Ive been doing that for
days so Ive gotten careless and id run my fingers right over tape in
cracks without looking, and one morning I felt a very powerful sharp pain
on my index finger and I jumped and pulled back my hand and then dropped a
pale white spider. I was shocked by how painful it was I had no time to
kill the spider it dropped and run away in 2secs. After realizing what
happened I tried to squeezed my finger and push out any venom, but all got
out was a little clear fluid and blood, the pain lasted for about 3hours
about 30min to an hour after the bite I felt a little sick, dizziness,
nausea. My finger at the site for the bite felt hard and nub for a while
after.
Kassy
03 Jun 2009, 14:13
Hi, I believe I have these critters infested in my truck. I cant really do
the vacuum way of exterminating since I can't seem to find where they are
coming from...sometimes they are outside sometimes inside. What kind of
bomb should I use...or any other recommended ways of ridding my vehicle of
these things before I wreck? lol
Ask the Exterminator
03 Jun 2009, 14:28
Buy a pesticide online called Kicker. It has a very high percentage of
pyrethrum which is an efficient flushing agent. If an insect is hiding it
will quickly run when it comes in contact with this stuff. Only problem is,
will it run into view or into deeper hiding?
Connie
11 Jun 2009, 01:21
I just found one crawling on the wall of my bedroom and killed it. Mind
you, I live in the middle of Boston, on the 8th floor of an apartment
building. I do dorm at school, and I moved back home about 3 weeks ago.
Back at school, I live about 10 feet from the woods. And...now I'm paranoid
as can be. Do you think it...came from somewhere in the city or possibly
from school? If so...I've got to check all my school stuff to make sure
there aren't other bugs around... Do you reckon there might be a nest on
anything? I'm really scared. I'm a city kid who has to go to the country
for college and I didn't expect to have to deal with this when I moved
back.
Ask the Exterminator
12 Jun 2009, 09:40
Spiders crawl toward lights. If your building has those nice decorative
night lights, you are going to have spiders. They follow flying insects and
flying insects fly towards lights.
Sac spiders are tiny and so are their capture sacs.
Megan
10 Jul 2009, 13:10
In which states are Yellow Sac Spiders native? What climates are they
accustomed to? I live in Ft. Collins, Colorado and have a moderate
infestation of various spiders in the basement. According to CSU's
website, sac spiders in general are common here, but no mention of the
Yellow Sac Spider which (though all sac spiders are common biters) scare me
more because of their brown recluse-like bites. I'm wondering if I should
keep an eye out for it, or if it is one less spider I have to worry about.
Thanks!
Ask the Exterminator
10 Jul 2009, 14:18
You can find them throughout the U.S.
Personally, I don't worry much about spiders in my home. They usually keep
to themselves and act as great little pest control helpers eating ants,
crickets and other insects that invade my home.
If my wife sees a spider I act, but I don't try to flush them out of every
crack in my century-old home. You might want to think co-existing.
Wayne
18 Jul 2009, 13:17
Several weeks ago, I sustained nighttime bites to the cheek and earlobe,
which I was fairly certain were spider in origin. These took just under a
week to heal, but now I am experiencing symptoms which resemble Lyme
Disease. From what you know of these little critters, could what I am
experiencing, possibly be a consequence? I have no evidence of tick bites
anywhere even though I garden extensively.
Ask the Exterminator
18 Jul 2009, 23:04
Spiders! Ticks! It does not matter. If you feel like you may have Lyme
disease get yourself to a doctor. It's nothing to mess around with.
Heather
03 Aug 2009, 02:14
I've been bittin alot by which I believe is this spider,there was bascally
a trail going up my forehead with 3bites they were red and one swelled up a
bit,and I was just wonder if there's something I can do to keep them out of
my bed room and chemicals are not realy a option and I've been bitten alot
more on my legs and arms. I can't not figure out were their coming from
there's like no end to them and for some reason they seem to me In my room
more seeing how I get bitten and my sister did only once!
Ask the Exterminator
03 Aug 2009, 08:46
From the outside of your house feel around your windows to see if you can
sense any cold air seeping out from the air conditioned interior. If you
can feel it, so can spiders. Those are the cracks that need to be sealed to
keep them out.
Darlene Bennett
10 Aug 2009, 17:37
we have a big spider about the size of the palm of my hand,it has long
brown legs with black on the ends.it has a yellow back with brown stipe
down the middle and big yellow dots on it but the dots get little when they
go down. do you know what it is?
Michelle
10 Aug 2009, 23:41
Hi there. We also live in an apartment and tonight as I sat on the bed to
watch t.v., a small yellow and almost transparent spider of about 2mm came
down. I looked on the bed and there were more. We found more than a dozen
crawling on the sheets and have noticed them in other areas of the home.
Are they attracted to fabric which can hold dust? If any other condition
matters, it has been very hot and humid and we've kept the windows open
lately. We live in upstate New York. Since they are so trasparent, it is
hard to detect them on anything but a black or white surface. Is there a
way we can track down their nest and remove them? What should we do in the
mean time? Many thanks!
Nicole Kundrat
20 Aug 2009, 17:04
One of these little suckers bit me on my bottom lip while I was napping. I
didn' wake up when it happene.. but I had a small bump on my lip. Within a
few hours my lip had swollen, my jawline hurt like hell, my gums on my
lower jaw are swollen... im finally getting a little pain.. but it got
infected pretty quick too.
Stan Sawyer
16 Sep 2009, 18:50
Over a period of about 5 years I've been bitten six times by this
particular spider. Every time I get bit it's during my sleep. It starts out
as an itchy mosquito bite like lump and within two to three days becomes a
5-6mm necrotic skin rotting lesion. It feels almost like someone is putting
out a ciggarette on my skin. I have never seen the spider that bites me,
but I have seen them in my house many times. I think these spider seek out
humans as a secondary food source when they cannot find typical prey. I'm
convinced they feed upon us for an easy blood meal.
joanna
10 Nov 2009, 22:39
i have received multiple bites on several occasions over the past few
nights and no one has figured out what they were. they took several hours
to a full day to appear, itch like a really bad mosquito bite, and get very
red and swell up to 2 inches in diameter. i'm convinced i get the bites
when i sleep, because i dont feel myself getting bitten and have never seen
an actual spider. the exterminator ruled out bed bugs, and then thought
perhaps they were bird mites coming in the window so they put up pigeon
spikes. now my dermatologist thought it was a spider bite based on the
size of the bite. the exterminator has come many times to spray, and i
vacuum and set up glue traps, but i havent seen any bugs. so far i haven't
gotten any more bites, but i'm worried i will again since it's happened
about 3 or 4 times already.
do these sound like the yellow sac spider bites and if so how can i get rid
of them?
joanna
10 Nov 2009, 22:40
i forgot to mention, i live in a pre-war building in manhattan.. if that
helps in ruling out type of insect. thank you!
pj
16 Nov 2009, 05:22
How do I set traps to find out what is biting me?