Cheiracanthium mildei, the northern yellow sac spider is one of the most common spiders in Northeastern America. However, it can be found throughout the entire USA.
The yellow sac spider can be identified by its greenish, yellowish color. During the daytime these spiders often hide in a small blanket of web under leaves and wood, but will often make their way into homes and hide in corners or under window sills.
Description of the northern yellow sac spider
The Yellow Sac Spider is one of the most common spiders found in Northeastern America. The abdomens are yellow to tan and often have a green tinge to the coloring. There is a darker stripe that runs lengthwise about halfway down the abdomen. The tips of their legs are often darker and the face of the cephalothorax is always darker.
Eyes
Yellow sac spiders have eight eyes. The eyes are all the same size and form four pairs of two eyes each.
Size
The body of the adult female will grow to about 3/8 of an inch (10 mm). If the legs are included, they can reach approximately 5/8 of an inch (16 mm) across.
Web
The Sac Spiders do not spin webs to catch prey. They are nocturnal hunters and during the day they will usually spin a web to create a thin cocoon-like sac to hide in. These are often found in the crease where a wall meets the ceiling or in windowsills.
Bites
Believe it or not, these little guys are one of the more dangerous spider species in the Northern United States. They are the most common spider to be bitten by and their bites are sometimes mistaken for that of the Brown Recluse. Although their venom is not nearly as dangerous as the Recluse’s, the bite can sometimes cause heavy swelling and even leave open sores.
There is a lot of bad info on the net that states that the Yellow Sac Spider uses the same cytotoxin as the Recluse does, but not as potent. I have recently learned from Rick Vetter, the top Brown Recluse expert in the world, that this is not true.
Cheiracanthium mildei Scientific Classification
- Kingdom: Animalia
- Phylum: Arthropoda
- Subphylum: Chelicerata
- Class: Arachnida
- Order: Araneae
- Infraorder: Araneomorphae
- Family: Eutichuridae
- Genus: Cheiracanthium
- Species: Cheiracanthium mildei
Distribution of northern yellow sac spiders in the USA
The northern yellow sac spider can be found throughout the United States. However, it is especially common in Northeastern America. Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.
Found in perennial garden in Plover Wisconsin. Body was over 1” long.
Hello Kay, thanks for uploading this great shot! This is not a yellow sac spider, it’s a female American nursery web spider (Pisaurina mira). Nursery web spiders are not medically significant: https://usaspiders.com/pisaurina-mira-nursery-web-spider/
This is not a sac spider. More likely pisarina nursery web spoder
Found in my water cup this morning in east Pennsylvania. I’ve found quite a few of these spiders in my apartment. Haven’t really found webs for them. His body, excluding his legs, are pretty thin and tiny.
Hello Sage, thanks for getting in touch. This is most likely a male yellow (or long-legged) sac spider, Cheiracanthium sp. They are not considered medically significant but can deliver a painful bite. Males are generally less venomous than females. You can read more about them here: https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
Hello,
I have been finding these spiders in my home everyday for months. How can I get rid of them? I’ve used home defense without any success.
Thanks in advance.
Found this spider on my screen door.. first I’ve found but seems to match your description.
Hello ET, thanks for getting in touch! Yes, this does very much look like a Chiracanthium yellow sac spider.
I think this spider is what I saw on my back door tonight?
This is in my flower pot at work
Spotted this one at work, moved it to a rise bush, happy I wasn’t bit!
This doesn’t seem to match anything except maybe the yellow sac spider and that’s not really a good comparison 😕
Hello Michelle, thanks for getting in touch! This is a beautiful European garden spider (or cross orbweaver), Araneus diadematus: https://usaspiders.com/araneus-diadematus-european-garden-spider/
Found this one in a house plant
Find these all over my house
Found this spider on my bathroom. First I’ve found to match your description.
Is this a yellow male or female sac spider bite? It is a red dot in the middle and a white ring around it but doesn’t sting or swell but it itches more than it is painful and it had a yellow back but didn’t know if it had a little stripe
Is this a sac yellow spider bite? The red dot and white ring it itches but is not painful
Lakewood Colorado
Found in dirty dishes. Not sure if it’s the yellow sac?
Zoomed in 10x to get this shot. It’s a small spider. Hangs out in my bathroom. Have seen two of em before.
Hello Sub, this is a yellow sac spider (Cheiracanthium sp.): https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
They are not medically significant but their bite can be painful.
Is this a Yellow Sac or Hobo? I found 12 so far near where ceiling and walls meet.
Hi Nelson, this is a Cheiracanthium sp. yellow sac spider.
I don’t know if this is a grass spider, yellow sac spider…? I seem to discover about 2 or 3 in every room. I would love if someone could identify it, though I realize it’s hard by this one picture.
Hello Marcus, this is a yellow sac spider: https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
Thank you so much!
Found on my windowsill in southeastern Wisconsin. Interesting pincer on the back and long, translucent legs. The body is small, not much larger than two match heads. Thanks for the identification!
Hello Terri, this is a male northern yellow sac spider (Cheiracanthium mildei): https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
This specimen surprised us running across our patio after dark in Columbus. With legs, it was bigger than a half dollar. Any ideas?
Sorry for low quality pictures. Is this a yellow sac spider/bite? I have seen these spiders on my car since camping in MN. My child also has a painful welt that looks raw in the middle on her head, wasn’t sure if it’s a spider bite. I’ll post the pic in another comment.
Hi Hayly, this is most likely a yellow sac spider – it could also be a ghost spider (Hibana sp.).
Sorry for low quality pictures. Is this a yellow sac spider bite? I have seen these spiders on my car since camping in MN. My child also has a painful welt that looks raw in the middle on her head, wasn’t sure if it’s a spider bite.
Hello, this is almost certainly not a spider bite. Spiders only bite in very extreme situations. Almost all bites occur when someone reaches into the spider’s web/burrow or when they are pressed against the skin when they hide in clothing. While one bite is rare, bites to the head are extremely rare, two spider bites to the head are close to impossible. This is much rather a bite of some insect.
This was running across our back patio after dark in Ohio. Any thoughts?
Hi Keir, this is a male nursery web spider (Pisaurina mira): https://usaspiders.com/pisaurina-mira-nursery-web-spider/
Hi! I found this one while gardening, i think it may have gotten picked up with the leaves i was shoveling. The body itself was nearly an inch in length. Is this a yellow sac?
Hi Maddy, I’m not 100% sure but I suppose this is a nursery web spider (Pisaurina sp.): https://usaspiders.com/pisaurina-mira-nursery-web-spider/
It’s not a yellow sac spider.
Not sure what this is
Hello John, this is a male yellow sac spider (Cheiracanthium mildei): https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
This one on my left and it bit me. I am in Indiana. I’m hoping it’s not poisonous.
Hi Colleen, I hope you are fine. This is a northern yellow sac spider – it’s not a medically significant spider but a bite can be painful: https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
Found two yellow sac spiders one blocking the entrance to catch wasps 😂. Fort Collins
I’m having problems identifying this spider. I believe it might be a sac spider. I found it in Wisconsin.
On my front door, Aloha Oregon
Looking to figure out what this little guy is, seen a lot of grass spiders recently but they all had markings, do juveniles look plain colored like this or is it another type?
Hello Jake, this is a yellow sac spider (Cheiracanthium sp.): https://usaspiders.com/cheiracanthium-mildei-northern-yellow-sac-spider/
I’m wondering if this is a yellow sac spider. Picture quality is not great but she seemed in a bad mood and I wanted to keep the screen between us.
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Does this look like a yellow sac spider? I’ve seen a few of them in the kitchen today. All of them have been quite close to me when I spotted them, which really freaked me out!
What’s this, a yellow sacred or crab spider?
Please help! Is this a yellow sac or brown recluse spider? Located in Kansas.
Joanne, I’m no expert, but looks like a yellow sac spider to me. Definitely not a brown recluse (in my non-expert opinion): it’s uniformly pale yellow (not shades of brown) and has no “fiddle shape” on its back like the brown recluse does. Also, it seems to be hanging out in a clean, brightly lit kitchen or something which is very much not the kind of place reclusive brown recluse spiders like to hang out.
Found this spider in my home where ceiling meets wall. Small thin caccoon.
In South West Michigan late Feb. on warmer day found in the kitchen. Should I be concerned?
Is this a yellow sack spider? Came home from work and it was on my bathroom sink and another on back of my tub. Sorry I zoomed in