Hobo Spider, Aggressive House Spider
Tegenaria agrestis
Agelenidae (Funnel Web Weavers), Order Araneae
Physical Description
The hobo spider has a robust body with a distinct, elongated oval-shaped abdomen and a relatively uniform brown cephalothorax. The surface is covered in fine, velvety hairs rather than being smooth or spiny. Unlike many other spiders, the legs are notably lacking in distinct dark banding, giving them a more solid, uniform brown appearance.
Size Estimate
Body length typically ranges from 11 to 18 millimeters for females and 8 to 14 millimeters for males. The total leg span can reach up to 40 to 50 millimeters, making it a medium-large house spider.
Coloration & Markings
The base coloration is a dull, dusty brown. The abdomen features a distinctive pattern of a yellowish or pale central herringbone or chevron pattern running down the dorsal side, though this can sometimes be faint or worn depending on the individual's age.
Web Type
Builds a characteristic funnel-shaped sheet web in hidden, low-to-the-ground locations. The web consists of a flat, densely woven horizontal sheet of silk with a tubular retreat at the narrow end where the spider waits for prey.
Eye Arrangement
Features eight small, dark eyes of roughly equal size arranged in two nearly straight horizontal rows of four across the front of the clypeus, which is typical for the funnel-web weaver family.
Leg Characteristics
Legs are moderately long, robust, and covered in fine hairs and spines. They are uniformly brown without any contrasting dark rings or bands, which helps distinguish them from wolf spiders or giant house spiders.
Venom & Safety Information
Venom Information
Possesses a necrotic venom, though scientific consensus on its medical impact has evolved. While historically feared for causing severe necrotic lesions, modern studies suggest many attributed bites were misdiagnosed or secondary infections.
Medical Significance
Considered of moderate medical significance. Bites can cause localized pain, redness, and sometimes a hard swelling or temporary lesion, but severe systemic effects or true tissue necrosis from hobo spider venom alone are rare and debated.
Safety Recommendations
Wear gloves when moving firewood or cleaning out dark basements or crawl spaces. If found inside, gently capture the spider under a glass and release it outdoors, or leave it alone if it is in an out-of-the-way location.
Habitat & Behavior
Habitat & Range
Native to Europe and Central Asia, the hobo spider was introduced to the Pacific Northwest of North America and has since spread. Prefers dark, humid, undisturbed areas near the ground, such as under woodpiles, in crawl spaces, basements, and around foundations.
Behavior & Temperament
Primarily nocturnal hunters, hobo spiders spend daylight hours hidden inside their funnel webs. They are defensive rather than aggressive, biting usually only when trapped against human skin or accidentally compressed.
Diet & Prey
Feeds primarily on crawling insects such as beetles, roaches, earwigs, and flies that happen to walk across the horizontal sheet of their funnel web.
Seasonal Activity
Most active during late summer and autumn, particularly around August and September when mature males actively wander in search of mates, frequently leading to increased indoor encounters.
Description
The hobo spider is a quintessential funnel weaver, recognizable by its mottled brown body and the signature herringbone pattern on its abdomen. Expert at constructing intricate sheet webs low to the ground, it plays an effective role in regulating household and garden insect populations.
Key Features
Uniformly brown legs lacking bands, a distinct herringbone pattern on the dorsal abdomen, and the construction of a low-profile funnel-shaped retreat web.
Similar Species
Often confused with the Giant House Spider (Eratigena atrica) and wolf spiders (Family Lycosidae). Giant house spiders are generally larger with banded legs, while wolf spiders actively hunt without webs and have noticeably larger anterior median eyes.
Life Cycle
Females construct tough, disc-shaped silk egg sacs in autumn, hiding them in sheltered areas. Spiderlings emerge in spring, go through multiple molts to reach maturity, and typically live for one to two years.
Ecological Importance
Acts as an effective natural pest control agent in and around human structures by preying on numerous crawling insect pests.
Conservation Status
Not evaluated by the IUCN, but populations are stable and widespread throughout its native and introduced ranges.
Interesting Facts
Despite its species name 'agrestis' (meaning 'rural' or 'of the fields'), this spider is frequently found in human habitations, earning an unearned reputation for aggression that contradicts its naturally defensive nature.
Photography Tips
Photograph from above to clearly capture the dorsal herringbone pattern on the abdomen and from the side to show the lack of banding on the legs. Use macro lighting in a safe containment container to avoid disturbing the spider.
Identified: 2026-08-19T18:14:54.277050