The hobo spider (Eratigena agrestis) is one of the most frequently encountered large spiders in Montana homes, particularly in the western part of the state. Originally from Europe, hobo spiders were introduced to the Pacific Northwest in the 1930s and have since spread widely throughout the region. They are funnel-web spiders, building flat, funnel-shaped webs in dark, low-lying areas, woodpiles, window wells, basement corners, and spaces under furniture.
Hobo spiders are fast runners and poor climbers, which is why they are almost always found at ground level. They are most active in late summer and fall, particularly August and September — when males roam in search of females, increasing the likelihood of encounters with humans.
Hobo spiders are frequently confused with the giant house spider (Eratigena atrica), a non-venomous spider that has largely displaced hobo spiders in urban areas over the past two decades. Accurate identification matters. Montana Pest Solutions technicians are trained to properly identify spider species.
Size
¼ – ½ inch body; leg span up to 2 inches
Color
Brown with chevron-shaped markings on abdomen
Active Season
August–October (peak encounter season)
Risk Level
Medium (venom potency debated; bite can cause localized tissue reaction)
Habitat
Ground level; basements, woodpiles, window wells
Web type
Flat funnel web
SIGNS OF INFESTATION
Identifying Hobo Spiders in Your Home
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Funnel-shaped webs at ground level — Flat, sheet-like webs with a funnel or tube at the back corner in basements, garages, and crawl spaces.
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Spider sightings at floor level — Fast-moving brown spiders at ground level, particularly in late summer.
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Webs in window wells — Window wells are a classic hobo spider habitat; funnel webs here are a strong indicator.
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Egg sacs in webs — Papery white egg sacs attached near the funnel entrance.
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Increased sightings in August–September — Roaming males during mating season dramatically increase encounter frequency.
HEALTH RISKS
The venom toxicity of hobo spiders has been a subject of scientific debate. Earlier research suggested their bites could cause necrotic (tissue-killing) wounds similar to brown recluse bites, but more recent studies have been less conclusive. What is agreed upon: bites can cause pain, redness, and local swelling. In some individuals, more significant reactions including headache, fatigue, and in rare cases, tissue damage have been reported. As with all spider bites, individuals with allergies or compromised immunity are at greater risk. Bites typically occur when a spider is accidentally trapped against skin — in shoes, clothing, or bedding.
PROPERTY DAMAGE
Hobo spiders cause no structural damage. Their webs are a nuisance aesthetic issue in garages, basements, and exterior corners.
