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How to identify it
- A light brown, fast-running spider with pale markings and a herringbone or chevron pattern on top of the abdomen. Body length figures differ: about 1/2 to 5/8 inch (UC IPM) or up to 3/8 inch (Utah State, for hobo and grass spiders together); UC gives 1 to 1 3/4 inches including legs.[1][2][5]
- Its webs are almost always hidden under objects and don't look much like funnels, unlike the obvious funnel webs of its relatives.[1]
- Many funnel weavers look alike. Telling them apart takes examining the reproductive structures under magnification, so identifications by non-specialists are usually wrong; Utah State asks people to verify a suspected hobo spider with Extension.[1][5]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Other funnel weavers (grass spiders) | Dozens of similar species build obvious funnel webs in vegetation and cracks; none cause necrotic wounds or serious injury.[1] |
| Giant house spider | A related European species that has displaced the hobo spider in places such as Seattle, and one that is easily confused with it.[1][8] |
Where it lives
UC IPM gives its North American range as the Pacific Northwest, from British Columbia east to Montana, Wyoming and Colorado and south through Oregon and northern Utah, and says no arachnologist had verified it in California. GBIF's 1990-2026 U.S. records (about 1,300, from 9 states on the map, including 2 each from California and Nevada) come mostly from Washington, Colorado and Utah. Indoors and out it webs in basements, window wells, woodpiles and around foundations.[1][2][10]
Biology and life cycle
Like other funnel weavers, it waits at its retreat and rushes out to grab prey; it eats insects.[1][5]
Utah State says hobo spiders are very common indoors between August and October, often found in tubs and sinks or running across the floor.[5]
Damage and signs
Health risk
The necrotic-bite claim traces to the 1990s, when a CDC report (MMWR, 1996) described three cases attributed to hobo spider bites in Idaho, Oregon and Washington and urged northwestern doctors to consider it. Later work did not hold up: hobo venom did not harm red blood cells in a Washington study, and spiders exposed to MRSA did not transfer it; in 33 verified spider bites in Oregon, including one by a hobo spider (pain, redness and muscle twitching that cleared in 12 hours), none caused dermonecrosis; and a Canadian review found hobo spiders have not been reliably linked to skin necrosis.[6][7][8][9]
Control
Keep them out
Seal cracks in the foundation and gaps around windows and doors, fit tight door sweeps, keep screens in good repair, and point outdoor lights away from doors and windows so they draw fewer insects.[2][3][5]
Sanitation
Remove clutter, woodpiles, rocks, leaf litter and heavy vegetation near the foundation, and vacuum or sweep webs and spiders regularly.[2][3][5]
Traps and physical control
Monitor traps catch wandering spiders, especially from August to October; single spiders can be vacuumed or carried outside in a jar.[5]
Pesticides
Insecticides don't give long-term spider control and generally shouldn't be used against spiders outdoors.[2][3]
Where the bite story came from
In 1996 CDC's MMWR summarized three cases attributed to hobo spider bites from Idaho, Oregon and Washington, noting such reports were rising in the Pacific Northwest.[6]
UC IPM notes that hobo spider venom isn't considered toxic to people in Europe, and that when venom from both European and Pacific Northwest spiders was tested in the same strain of rabbits used in the original work, neither produced necrotic wounds.[1]
Doctors are urged to diagnose a spider bite only when a spider is caught biting or otherwise reliably tied to the wound, because many other conditions, including bacterial infections, cause similar lesions.[9][7]
Common questions
- Do hobo spiders cause flesh-eating wounds?
- The evidence says no. Verified bites in Oregon caused no dermonecrosis, venom tests found no harm to red blood cells, and a Canadian review says hobo spiders have not been reliably linked to necrotic wounds.[8][7][9]
- How do I know if it's really a hobo spider?
- You usually can't by eye: many funnel weavers look alike and species are told apart by their reproductive structures. Utah State Extension will verify an identification.[1][5]
- When are hobo spiders most common indoors?
- Between August and October, when wandering spiders turn up in tubs, sinks and along floors.[5]
Sources
- University of California Statewide IPM Program, “Pest Notes: Hobo Spider, Publication 7488 (November 2015).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnhobospider.pdf (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: Spiders, Publication 7442.” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnspiders.pdf (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: Widow Spiders and Their Relatives, Publication 74149 (revised March 2017).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnblackwidow.pdf (accessed 2026-11-11)
- iNaturalist, “Eratigena agrestis taxon page (order and family).” www.inaturalist.org/taxa/454859 (accessed 2026-11-11)
- Utah State University Extension, “Hobo and Grass Spiders (IPM for nuisance pests).” extension.usu.edu/planthealth/ipm/notes_nuisance/hobo-grass-spiders (accessed 2026-11-11)
- Centers for Disease Control and Prevention (MMWR), via PubMed, “Necrotic arachnidism, Pacific Northwest, 1988-1996, MMWR 45(21):433-436 (1996).” pubmed.ncbi.nlm.nih.gov/8618542/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Journal of Medical Entomology, via PubMed, “Gaver-Wainwright MM, Zack RS, Foradori MJ, Lavine LC (2011), Misdiagnosis of spider bites: bacterial associates, mechanical pathogen transfer, and hemolytic potential of venom from the hobo spider, Tegenaria agrestis, Journal of Medical Entomology 48(2):382-388.” pubmed.ncbi.nlm.nih.gov/21485377/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Toxicon, via PubMed, “McKeown N, Vetter RS, Hendrickson RG (2014), Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity, Toxicon 84:51-55.” pubmed.ncbi.nlm.nih.gov/24726469/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Canadian Family Physician, via PubMed, “Bennett RG, Vetter RS (2004), An approach to spider bites: erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada, Canadian Family Physician 50:1098-1101.” pubmed.ncbi.nlm.nih.gov/15455808/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Global Biodiversity Information Facility (GBIF), “Eratigena agrestis (hobo spider): occurrence records in the U.S., 1990-2026 (GBIF occurrence search).” api.gbif.org/v1/occurrence/search?taxonKey=7909042&country=US&hasGeospatialIssue=false&occurrenceStatus=PRESENT&year=1990%2C2026&facet=stateProvince&facetLimit=400&limit=0 (accessed 2026-11-11). State counts are records reported (iNaturalist research-grade, museum specimens, surveys), not abundance; funnel weavers are often misidentified as hobo spiders.