Agelenopsis – American Grass Spider

Agelenopsis, American grass spiders, are a genus of spiders that can be found around the world and in every US state. They are some of the fastest spiders in the United States and can be fun just to watch if you can trigger the web right.

Using a long piece of a weed or grass, try tickling the web as a bug would, if it was struggling across the web. If you do it right, the Grass Spider will run out with lightning speed, looking for a meal.

Then again, if you don’t mind seeing it, you can always throw a bug in its web.

Quick Overview: Agelenopsis – American Grass Spider
Medically significant: No
Body size: 3/4 inch (19 mm)
Main colors: brown, black
Range: Throughout the United States
Web: Funnel-shaped web

Agelenopsis Description

The abdomen is oblong, with long spinnerets at the end. Most species of the American Grass Spider have a pattern of stripes running from front to back. On the abdomen, there are often two white stripes, which are broken into many sections. The Cephalothorax on the other hand, has the lighter stripe running down the middle, dividing two dark stripes.

Photo of the size of an american grass spider
Photography by: K. J. Ester – Macomb Mi.

The grass spider is often confused with some similar looking species of the wolf spider or the American Nursery web spider. In the Pacific Northwest, the grass spider’s distribution overlaps with the related hobo spider (Eratigena agrestis) and the giant house spider (Eratigena atrica). Both of these spiders are also part of the funnel-weaver family (Agelenidae) and have a similar appearance to the grass spider. The best way to distingiush the grass spider from these species are the clear three lighter lines that run along the cephalothorax (head) of the grass spider. Hobo spiders and giant house spiders don’t have these longitudinal lines but other, less-distinctive markings.

Eyes

Grass spiders have eight eyes. The eight eyes are all similar-sized and form an oval shape. You can see a closeup photo of the grass spider eyes below:

Agelenopsis grass spider eyes closeup high resolution
The eye pattern and fangs of a grass spider. Photo used with persmission from Chase Noble

Size

The bodies will grow to 3/4” (19 mm) from front to back, and approximately 1 ½” (38 mm) including the legs.

Agelenopsis grass spider closeup high resolution body top view
An american grass spider. Photo used with permission from Chase Noble.

Web

They always spin their webs horizontally, creating a thick floor, which will feed into a funnel at one end. The spider hides in the funnel section, waiting for its next meal to crawl upon its web. However, the webs are not the sticky kind, which are used to trap prey. Instead, they trigger vibrations on the web, which the spider feels. The Grass Spider then uses its speed to charge and attack its prey.

Grass spider in funnel web agelenopsis
A grass spider in a funnel web photographed by Roxie in Alabama

Grass spider bites

The Grass Spider is considered quite harmless to humans. They stay in their webs and do not venture out unless forced to do so. A bite can cause some local swelling, redness and itchiness but is not dangerous.

Agelenopsis spider in the USA
Photography by: Paige Borgeson – Muskegon, Mi.

Agelenopsis Scientific Classification

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae
  • Infraorder: Araneomorphae
  • Family: Agelenidae
  • Genus: Agelenopsis

Other common names

The Grass Spider is also known as the American funnel-web spider or funnel weaver. It is not to be confused with the Funnel Web Spider, which is a very dangerous spider in Australia. To limit confusion, we strictly stick to the name American grass spider or grass spider.

Distribution of the American grass spider in the USA

Agelenopsis Grass Spider Range

Various species of the American grass spider can be found throughout the United States – 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

Grass spider photos

Here are some more photos of grass spiders that have been submitted by our readers:

Agelenopsis – American Grass Spider

87 thoughts on “Agelenopsis – American Grass Spider

    1. Hey Jerry, thanks for getting in touch! Yes, you can absolutely keep a grass spider as a pet. Grass spiders are funnel weavers and create funnel-shaped webs. Make sure to add some twigs and leaves in one area/corner of the enclosure where it can set up its web.
      Here is some more information:
      https://www.wikihow.com/Keep-Grass-Spiders

      1. This was found in my house (south/east) Michigan. I couldn’t squish so I put a glass over it. Was still alive 3/4 days later (no webs inside of inverted glass) Released into yard, after looking into and thinking it was best. Any feedback? Did I screw up?

    2. Hey, would you say this is the same spider as above? They tend to find their way into the house and I have small several small pets.

  1. Is this a grass spider? Found in northern MN. I have a lot of these in my house. The orange-ish oval on its back is making me question it. It’s approx: 1/2 inch

      1. Hello,
        Can you help me identify this spider that I found in my bathroom? It looks so similar to an American Grass spider but also a Rabid Wolf spider. It’s being quarantined under a glass dish until I can find out if it’s poisonous. Thanks!

  2. Found this spider just inside my back door? I didn’t see any photos on your site that look like this.

    1. Hi John, thanks for the photo. This is some type of funnel-web spider of the family Agelenopsis. It could be Agelenopsis naevia but it’s hard to make an ID off the picture alone. It would help if you could mention the location where you found the spider.
      Regardless of the exact genus or species, Agelenopsis spiders are not medically significant. You can read our overview of the similar and closely related American grass spider here: https://usaspiders.com/agelenopsis-american-grass-spider/

  3. O-0 big ol’ quarter sized spider found in northern utah, no web. Primarily brown and gray(?)

  4. Hi! Nashville Indiana here…
    This medium sized guy came to visit me in my garden tonight. Your thoughts on who he is is greatly appreciated!

  5. Hi, I found a spider who looked exactly like the one used as the main example for American grass spiders before clicking the the “more” link in my kitchen sink tonight. It was definitely NOT the size of a quarter – more like a half dollar, and probably a bit larger, still. As I had no idea what it was and my three year old was at my side, my only concern was making sure I secured my home but it didn’t seem to be bothered by the pot of water potted on it and it couldn’t scale the sink basin to get out. Could it have been a harmless grass spider? Do they get that big?

    1. Hello Denise, yes, grass spiders can get that big. It might have also been a giant house spider (Eratigena atrica) – they look somewhat similar: https://usaspiders.com/eratigena-atrica-giant-house-spider/
      It depends on your location. None of the large brown spiders that look similar to grass spiders in the U.S. are medically significant. The only medically significant brown spider is the brown recluse which is not that big and looks different.

  6. I live in New Jersey, and I saw these two spiders this evening by the garage. I’ve never seen this kind of web before. I took another photo from the side to show you what their bodies look like. What kind of spiders are they?

    1. Hello Barbara, it’s hard to ID them just off their webs – they could be some type of cobweb spiders or even orb weavers with the web on the left belonging to a different species. Can you upload the picture of the spider itself to the reply here? That will help with the identification.

  7. This spider has been in a corner of my garage (Michigan) for a while and has built a pretty impressive web that it likes to stay in. I think it’s a grass spider?

  8. Do you guys think these are the same spiders? Found in Southeastern WI.

    Spider 1: found on garage, no web located.
    Spider 2: found by patio door, funnel web located nearby.

    Both grass spiders?

  9. Found inside house on wall in living room in Orr, Minnesota. Hairy legs. Size of a quarter. Who is this guy? Please help. Thank you!

  10. Found this in Baltimore Maryland. It was on my closet door, threw a Gatorade bottle at it and it ran so fast it almost got away if it wasn’t so big.

  11. Found this hairy dude in Northern New Hampshire. I am hoping you’re able to identify it. I’ve been looking but and not sure what it is. I appreciate your assistance and thank you for your time answering everyone’s questions.

    Thank you!

    1. Hello there, thanks for getting in touch! This is a male fierce orbweaver (Araneus saevus). Despite its name, this spider is not aggressive or dangerous. It can be safely relocated.

  12. This is the second spider i have recently found in my house. First on was in my kitchen this one was by my pillows i just happened to notice as i was laying down for bed.

  13. My daughter found this fellow. I can’t decide if he’s a grass spider or giant house spider. Now free, but his size gave her quite a scare.

  14. not sure what kind of spider this is, i found it in a funnel shaped web in my car its been there three days and its about the size of a dime and it is shy but i put a bug in the web and it was very quick. can you help?

  15. Ugh! I found this VERY LARGE dead spider floating at the bottom of my horse trough. This pic is through a foot of water. I scooped it out with a fish net, but even tough it was dead, I was still too scared to put my hand next to it for a size comparison. I was about the size of a half dollar. Largest spider I’ve ever seen. I’m in Granite Falls, WA. Pretty sure it’s a Grass Spider.

  16. Hello, we have this friendly spider living in our kitchen and we feed him crickets from time to time. Assuming he is an agelenopsis, what is their expected life span in an indoor environment where cold weather is not a concern? We have named him “Mr. Brain” 😆

    1. Hello Tim, yes, Mr Brain is a grass spider. Their lifespan is usually around one year – they will usually die with the first frost after laying eggs. If you keep the spider inside during the colder time of the year, there is a small chance that it might survive a few months extra. But it will be unlikely that it will live through spring.

  17. I have hundreds of these little guys in my garden, but only in my garden, no where else. Their body is only about 1/8 inch long. Are they grass spiders and why do they like my garden so much?

    1. Hello Darla, thanks for getting in touch! This is a wolf spider. You are probably seeing many as they might have emerged from one or a few egg sacs in your garden. They are not medically significant.

  18. Any idea what kind of spider this is? Looks kind of like a grass spider, but the body is wider. Maybe pregnant? It was bigger than a quarter.

  19. We found this guy living in our bathroom sink in Sterling, VA. It’s building a somewhat disorganized web (as far as I can tell) on the surface of the basin and around the drain. It moves quickly around the basin. Any ideas?

  20. Once I’d been scraped off the ceiling, your site helped me identify this as a grass spider and prevented me from grabbing my dog, my purse, selling the house, and moving to a hotel permanently. It was found on one of my little dog’s sweaters just as I was about to put it on her. I’d taken it from a pile of sweaters in a darkish corner of my living room where I’d left them since last winter. I’m sending a picture because I thought it would be a helpful one for identification.

    1. Hello Pamela, thanks for getting in touch! I’m glad you didn’t have to move out of your house 🙂 This is a great shot of an American grass spider – thanks for sharing it!

  21. For starters, thank you so much for what you are doing here. It’s great to be informed on whether or not some of these spiders could be a threat to humans or pets and the information you have is so wonderful. I am not a fan of anything that crawls but I do try to keep an open mind with spiders as long as they won’t harm me or my family.

    On that note I’m curious about this big guy/gal I found in my garage. Everything I’m reading is pointing towards grass spider but being in mid-southern Indiana and the coloring/pattern I’m wondering if maybe it could be a wolf spider. Any help would be appreciated!

    1. Hello Christina, thanks for the kind words!
      This is definitely a grass spider, not a wolf spider. The body shape and color patterns can look very similar for the two spider families. But the long spinnerets at the back of the abdomen are a sure giveaway that this is a spider in the family Agelenidae (grass spider).

  22. Found in my backyard in San Francisco, CA. There are a bunch of them crawling through the grasses and bushes. Some are bigger and more elongated than others.

  23. found this one this morning. it blends in so well…. is this a grass spider? just a shade bigger than a big half dollar.

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