The Steatoda triangulosa, commonly called the triangulate cobweb spider is a brown-black spider found throughout the US. It has an iconic triangulate shape on its back.
Steatoda triangulosa Description
The most distinguishing marks on the Steatoda triangulosa are the two darker zigzag markings that run down the abdomen, which form a set of triangular shapes running down the middle between them. They are usually two-toned brown spiders with banded legs.
Size
The Steatoda triangulosa is not a big spider as the body of the adult female reaches only about 1/4 of an inch (6 mm). With the leg spread, it reaches approximately 5/8” (16 mm).
Bites
Though some species of the Steatoda family can have medically significant bites, I have not found any evidence of anyone receiving a bite from the S.triangulosa. I have found two different places on-line that says they are harmless, one of them saying they are too small to puncture human skin. Personally, I tend to believe all spiders can bite, but it does sound like the Steatoda triangulosa is on the harmless side.
Scientific Classification of Steatoda triangulosa
- Kingdom: Animalia
- Phylum: Arthropoda
- Subphylum: Chelicerata
- Class: Arachnida
- Order: Araneae
- Infraorder: Araneomorphae
- Family: Theridiidae
- Genus: Steatoda
- Species: Steatoda triangulosa
Distribution of the Triangulate Cobweb Spider in the USA
The Steatoda triangulosa can be found in every state in the United States and Canada. 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
Following are several photos, the first is a belly shot, the last is a side shot, the 2 middle are top body shots.
https://photos.app.goo.gl/BWLWHYS28Ay3zV9y5
Hello Susan,
Thanks for the images. The quality makes it hard to make a definite ID. But given the body shape and coloration, I am fairly certain that this is some species of false widow spider (Steatoda sp.; not medically significant). My first guess would be Steatoda triangulosa: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/ or Steatoda grossa: https://usaspiders.com/steatoda-grossa-false-widow-spider/
I found a tiny spider in my kids toy box i am not sure what it is can anyone help me and if it is bad
Good day! I had found a tiny, web-residing spider in my room that I have been trying to identify for the past hour but have had no luck. Unless it’s a species that has recently started to migrate to this area, hopefully stating that this is on North Georgia should narrow it down.
Hello Diane, thanks for uploading this picture. This is not a triangulate cobweb spider. It’s some type of orb weaver spider. Given the shape of the abdomen, I am fairly certain that it is a Mangora species. My best guess is Mangora placida: https://bugguide.net/node/view/1348149
I’m my hotel that is just outside FT. Lee VA. Had just caught a fly in its web. I took two videos of it wrapping the fly up. Any idea?
Hello Mitchell, thanks for reaching out! This is most likely a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
They are a close relative of the black widow but not medically significant. A bite can be uncomfortable, though.
Hi.. this guy or gal was sitting in my bedroom this am. Am hoping it’s a a good spider so I can put it outside to eat insects! Marsville, WA
Hi Shelly, thanks for reaching out! This is one of the good ones 🙂 it’s a male false widow spider, most likely a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
I’ve looked all over online and I can’t seem to correctly identify the spider. Any help would be appreciated as my cabin is infested with them currently. I live in North Alabama 15 minutes from either Tennessee or Georgia.
Hello Shawn, thanks for getting in touch! This is a triangulate cobweb spider (Steatoda triangulosa). It’s a close relative of the black widow spider but not medically significant. You can read more about it here: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
I found this underneath of a bicycle, which I pulled from the garage. It was probably the size of a dime. This is near Greenville, SC.
Hello Amanda, thanks for uploading this great shot! This is a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Found in Sonoma (NorCal California)…walking across bathroom floor. No sign of a web. Medium size, maybe 1/2 inch body, with legs 1-1.5 inches. Reddish brown color, with what seemed to be gray or cream markings. Thanks 🙂
Hello Georgina, thanks for getting in touch! This is definitely a male false widow spider (Steatoda sp.). They are close relatives of the black widow and can deliver a painful bite but are not considered medically significant. Male specimen are generally considerably less venomous than females. This fellow is most likely a male triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
What is this? Very tiny: maybe 3/8” and hundreds of them hanging out on a wood crate, NE OK. Many are barely visible they are so small and nearly colorless.
Finally caught this spider in my cupboard..been after it for over a year…it was hiding inside the handle of my pressure cooker with 5 egg sacks..4 were empty, one sack full and there was also a much thinner and more elongated spider skin with them…does this spider that looks just like a black widow except for the yellow zigzag lines kill its make too?
Hello Jennifer, thanks for getting in touch! This is a triangulate cobweb spider (Steatoda triangulosa). They have a similar body shape of black widows as they are in the same spider family. But they are not considered medically significant. The egg sacs are probably of the cobweb spider too. During their lifecycle, they molt several times, so the skin is probably hers too. You can read more about them here: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Found this spider Las Vegas NV
Reddish brown body and legs
Black and white abdomen
Crawling on counter no web
Slightly smaller than a penny
Hello Travis, thanks for getting in touch. This is a male cobweb spider (Steatoda sp.). They are not medically significant. The male spiders of the different species in this genus look quite similar and it’s hard to make out the exact pattern on the spider’s abdomen on this photo. So an exact identification is impossible. It could be Steatoda triangulosa: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Western, NY found in my basement.
Hello Miranda, thanks for sharing this great picture. This is a female triangulate cobweb spider (Steatoda triangulosa). The white balls are egg sacs. It is a close relative of the black widow but not a medically significant spider: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
ID? Very small. 3/8ths-ish including legs. Found it and it’s hundreds of family mbrs in a wooden palette.
Male triangulate spider? He lives in my bathroom.
I’m no expert, but that is basically exactly the same little guy I just found in my bathroom. The one I found was super small, like no bigger than a dime (legs included). I think it is a triangulate cobweb spider (Steatoda triangulosa) – maybe a male? Idk. Really just commenting bc I hope an expert will weigh in…
With legs stretched out about size of quarter. Was getting bites 2-4x a night until I was able to kill it, but didnt smash it so I could identify. Bites looked like large mosquito bites with irregular borders. Thought it was hives at first. Would eventually become a deep red dot and itch for a week or so. Thinking it might be a Hobo Spider, but something is off. I live in the East Bay/Northern California. Please help me to identify.
Hello Adam, thanks for getting in touch! This is a cobweb spider (Steatoda sp.), most likely Steatoda triangulosa. Spiders usually only bite to subdue small prey or if the feel threatened. It’s highly unlikely that a spider would bite a human at night, especially several times. We as humans are way to large for them and there would be no point for them to bite humans. The bites are most definitely from another small animal that was feeding on your blood (spiders don’t do that).
Here is more information about this spider: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
find mostly in corners of restroom, under toe spaces of cabinets and around fireplace in Houston Texas
Hello Robin, this is a male triangulate cobweb spider (Steatoda triangulosa). It’s not a medically significant spider: https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
My son was bitten by a spider in several locations on his foot. He had an allergic reaction that entailed painful blisters. I found this spider in the same room the day later. Sorry I had to kill it. Today I was vacuuming and found a nest that had several sacks. I am hoping you can let me know if the eggs hatched. I also have pictures of the bites.
Just found this slightly larger than quarter sized spider crawling on my couch (yikes). Was able to snap some photos before I coaxed it outside with a paper towel but was wondering what the heck it was and if it could have been dangerous? Body size was like around half inch, legs plus body = a little big bigger than a quarter. Coloring may be off bc it’s a flash photo, but it was some shade of brown. The pattern has me stumped. I’m located in central New Jersey. Please help me ID this little guy/gal.
Located in Evans, Ga
What type of spider is this?
I found it in my kitchen. This is the second one but search gives me one venomous and one harmless
Hello Shanti, thanks for getting in touch! This is a female cobweb spider (Steatoda sp.) – most likely a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
It’s a relative of the black widow but not medically significant.
On wall in Houston, Tx
Hello Chris, this is a male cobweb spider (Steatoda sp.). They are close relatives of the black widows but are not medically significant.
I killed this spider in Holland, MI in my kitchen sink. I cannot find a similar spider online. Can you help identify it?
Hairs all over brow and black legs longer size less than quarter
Can you tell me what kind of spider this is?
Found this Steatoda triangulosa with beautiful blue triangles in a shed in Jessup, Maryland:
Live in Northern Mississippi. Found in a stack of scrap wood in my garage. Never seen this one before! About the size of a dime.
Hi Wade, this is a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
This little fella unfortunately lost his life startling me by descending onto my shoulder in my bed. Found in Camanche, IA. Rather small, only about a centimeter. Wondering if this is the critter thats been biting me and leaving an itchy double bump.
Hello Matthew, this is a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Hey there,
Found this little one in the northwest suburbs of Chicago – probably 5-6mm across. Any thoughts if it’s a cobweb spider?
Thank you!
Found this in my closet by my front door. Any confirmation if this is a triangulate cobweb spider?
Found this in the backyard in our hose cabinet. Seems similar to this spider but the white band around the abdomen (on the sides) makes me uncertain.
Northern California Coastal area.
What might this be? I did a catch and release but want to be sure we don’t have dangerous spiders in the yard.
Thanks!
Hi Magee, this is a noble false widow (Steatoda nobolis): https://usaspiders.com/steatoda-nobilis-noble-false-widow/
They have been introduced from the UK and are very common in California.
If you are interested in learning more about spiders in California, check out our California spider identification and information book – available as an ebook here or as a printed paperback on Amazon.
Found in Minnesota. It has a round bulbous body with white markings that appear to be spots or triangle shaped.
Hi Kelsey, this is a female triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Can anyone tell me what this is? It kind of looks like a common house spider, but someone told me it looked like a false widow.
Found in tucked up in a fan in the garage in Greenville, MS. Probably common, but I am not familiar with it. Fairly small with fat round body, could not see head well, the picture makes the body look a little more yellow than it is.
Hello Kathy, this is a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Small lots of them
Hi Terri, this is a triangulate cobweb spider (Steatoda triangulosa): https://usaspiders.com/steatoda-triangulosa-triangulate-cobweb-spider/
Hi all,
We’ve seen several of these small spiders in our home. Someone suggested it might be a male black widow but based on the photos above it clearly looks to me to be a triangulate cobweb spider.
I know the quality of the photos is not amazing but does my guess seem reasonable or any reason to believe otherwise?
Thank you!
This little friend has been living happily in our bathroom window for the past 8 months (in the Los Angeles area) taking care of our flies and is content to never leave the web as long as we sprinkle a little water on it every few days. She/he has molted twice and is now showing a light tan “sea-turtle” shape on her/his back. No markings at all on underside. Body is just under 1cm in length. Web is very messy. Thinking false widow or triangulated? Thanks!
Found this in my basement with TONS of old egg sacs and molted shells around it.
I found this outside right under my roof, only comes out on its web at nighttime in Ohio. Not sure what it is exactly.
For the past few weeks, this little spider has been living inside one of my tarantula enclosures! When I go to feed my tarantulas, I make sure to grab a tiny little cricket for him as well! He seems to enjoy the thought! I couldn’t ever identify him, but now I’m thinking he might be a Triangulate Cobweb spider! Would love a confirm, but either way, he’s welcome to stay!
Yes Hello i have found two spiders in our bedroom and i want to know if they are harmless or not. We have two little daughters and i just want to make sure that these spiders do not cause harm? We live in Tulsa Oklahoma
Found this guy in my slipper. Thinking it’s a cobweb spider but would appreciate your expert opinion.
This spider family lives on the opposite side of our 2nd story kitchen window. (only the female is pictured) but there’s a smaller one that looks similar in the same web and there were a bunch of baby spiders a few weeks ago in the web too. I’m wondering what kind of spider this is- none of the pictures looks like it!
Found this spider wrapping up a moth in my garage.