Hobo Spiders (Eratigena agrestis) – Identification, Risks, and Control

I have inspected some of basements, warehouses, and homes over the years, and few spiders cause as much misunderstanding as the hobo spider (Eratigena agrestis). Many people still believe this brown spider is dangerously venomous. In reality, the truth is more balanced: it can bite if trapped, but serious reactions are rare.

Hobo spiders belong to the family Agelenidae, known as funnel-weaving spiders. They build sheet webs with a tunnel-like retreat. Their behavior and appearance make them easy to confuse with brown recluse spiders, house spiders, or wolf spiders, leading to needless fear.

They are now found across North America, Europe, and parts of Asia, often living close to humans in basements, garages, and crawl spaces.

Identification

Correct identification is the first step before any pest control action.

• Scientific name: Eratigena agrestis

• Common name: Hobo spider, aggressive house spider (older name)

• Size: Adult body 7–14 mm long; leg span up to 5 cm.

• Color: Brown with a lighter stripe running down the center of the back. Abdomen shows several herringbone (chevron) patterns.

• Eyes: Eight arranged in two rows.

• Web: Flat sheet web with a funnel leading into a crack or crevice.

• Behavior: Fast runners; usually seen in late summer when males search for females.

Differentiation tips:

• Unlike brown recluse spiders (Loxosceles reclusa), hobo spiders do not have a violin mark on the cephalothorax.

• They are bulkier than common house spiders (Parasteatoda tepidariorum) and move quickly in open areas.

• Females rarely leave their web; males wander and are more often noticed indoors.

Biology and Ecology

Hobo spiders are nocturnal hunters. They do not use sticky silk to catch prey but rely on their funnel web to detect vibrations.

Life Cycle

• Eggs: The female lays 40–100 eggs in a silk sac, usually hidden under stones, boards, or basement debris.

• Development: Spiderlings hatch after about one month and grow for 12–18 months before becoming adults.

• Longevity: One to two years, depending on temperature and food availability.

They feed mainly on flies, ants, beetles, and other spiders. By controlling insect populations, they serve an ecological purpose. They prefer moderate humidity and stable temperatures, which is why basements and foundation cracks are ideal.

Cold climates slow their growth but do not kill them; they enter a semi-dormant state during winter.

Global Distribution

Originally native to Europe, Eratigena agrestis was accidentally introduced to North America in the early 1900s, likely through shipping routes.

• Europe: Common in central and northern regions such as the UK, Germany, and Scandinavia.

• United States: Established across the Pacific Northwest (Washington, Oregon, Idaho, Montana, Utah).

• Canada: Found mainly in British Columbia and Alberta.

• Asia: Recorded in parts of Kazakhstan and western Russia.

• Australia: Not established but occasionally imported through cargo.

In most regions, they prefer temperate zones and avoid very hot or dry conditions.

Risks and Damage

There has been confusion for decades about whether hobo spiders are dangerous to humans. Early medical reports suggested necrotic bites similar to brown recluse bites, but later research—including controlled studies by the CDC—showed no confirmed cases of serious tissue damage.

Realistic risks:

• Mild bite with redness and swelling in sensitive individuals.

• Allergic reaction or secondary infection if scratched.

• Psychological fear leading to panic or unnecessary chemical use.

For businesses, especially hotels or food shops, spider sightings can still cause customer complaints even if the species is harmless.

Unlike cockroaches or ants, hobo spiders do not contaminate food or transmit disease. The main issue is perception and nuisance.

Signs of Infestation

Hobo spiders are shy, but there are clues:

• Funnel-shaped webs along baseboards, behind furniture, or under storage boxes.

• Spiders running on floors at night (usually males).

• Egg sacs attached to corners or in cardboard boxes.

• Shed skins and fine silk debris near walls.

Because they need ground contact for web structure, infestations usually start at floor level, not on ceilings.

Control Methods

1. Inspection

Start by checking basements, window wells, garages, and unused storage. Identify webs and possible entry points such as vents, cracks, or gaps under doors.

2. Sanitation

• Remove clutter, cardboard, and stored clothes from floors.

• Vacuum regularly, including corners and under appliances.

• Seal or replace damaged window screens and door sweeps.

3. Physical Removal

• Use a vacuum to remove spiders and egg sacs directly.

• Dispose of the bag immediately.

• Sticky traps placed along walls can catch wandering males.

4. Exclusion

Seal gaps around pipes, electrical conduits, and wall cracks with silicone.
Reduce outdoor lighting to limit the insects that attract spiders inside.

5. Chemical Control

If population is high:

• Apply residual insecticide (e.g., bifenthrin or deltamethrin) along baseboards, under furniture, and near entry points.

• Avoid broad spraying on walls or near food.

• Always follow the label; misuse can cause resistance or health risks.

For large commercial buildings, a licensed pest control technician should conduct treatments with proper safety gear and monitoring.

Advanced Approaches

Modern pest management focuses on Integrated Pest Management (IPM) rather than pure chemical use.

• Monitoring: Install glue traps in corners to evaluate activity.

• Moisture control: Dehumidifiers reduce both insects and spider harborage.

• Insect reduction: Since spiders feed on other pests, managing flies, ants, or moths will naturally lower spider numbers.

• Education: Staff in commercial settings should learn identification to prevent false panic.

In sensitive environments (hospitals, food facilities), vacuum removal combined with crack sealing is safer than insecticide use.

Cultural and Historical Context

The hobo spider gained its dramatic reputation in the 1980s when media in the United States labeled it “the aggressive house spider.” This came from misidentified bite reports and confusion with other brown spiders. Later research corrected this myth, showing that the hobo spider is defensive, not aggressive, and generally avoids humans.

In Europe, where it originated, the species lives quietly in gardens and sheds without any medical reputation. Cultural fear mainly spread through social media and exaggerated pest-control advertising.

Interestingly, some traditional European farmers saw funnel-web spiders as good luck, believing they protected crops by eating flies and beetles.

Frequently Asked Questions

1. Are hobo spiders dangerous?
No. Their venom is mild and causes only local irritation in most cases. Necrotic bite claims are not scientifically supported.

2. What do hobo spiders eat?
They feed on insects like flies, ants, silverfish, and small beetles that get caught in their web funnel.

3. How can I tell a hobo spider from a brown recluse?
Hobo spiders have no violin mark, and their abdomen shows clear chevron patterns. Brown recluse spiders have six eyes, not eight.

4. Do hobo spiders make webs inside houses?
Yes. They build funnel-shaped webs near floors, behind furniture, or in basement corners.

5. Can hobo spiders bite humans while sleeping?
Only if trapped between skin and bedding. They prefer to escape rather than bite.

6. How do I get rid of hobo spiders naturally?
Keep areas clean, vacuum often, and reduce insects that serve as food. Peppermint or citrus oils may help but only for short time.

7. Where do hobo spiders come from?
They are native to Europe but now common in North America, especially in the Pacific Northwest.

8. What season are hobo spiders most active?
Late summer and early autumn, when males roam in search of females.

9. Do cats or dogs get bitten by hobo spiders?
It’s possible but rare, and bites are mild. Pets usually ignore them.

10. Should I call a pest control company for one hobo spider?
If it’s an isolated sighting, no. For repeated sightings or customer complaints, a professional inspection is worth it.