Hobo spiders, scientifically known as Eratigena agrestis, are common funnel-web spiders. Originally from Europe and Central Asia, these spiders have established populations in western North America, particularly the Pacific Northwest and Great Basin. Understanding how to accurately identify these spiders is important to differentiate them from other species.
Physical Characteristics of Hobo Spiders
Hobo spiders are medium-sized arachnids. Females measure 9 to 18 millimeters in body length, while males are slightly smaller, ranging from 8 to 15 millimeters. Their leg span can extend up to two inches, approximately twice their body length.
They are brownish-gray. The cephalothorax is often light to medium brown or tan and can display a chevron-shaped pattern. The abdomen, which is oval-shaped, often exhibits multiple chevron (V-shaped) patterns that point towards the head, though these markings can sometimes be faint.
Hobo spiders have uniformly colored legs that lack distinct dark bands at the joints. Their bodies are somewhat robust and covered in fine hairs, giving them a slightly fuzzy appearance. They possess eight eyes arranged in two horizontal rows. A key identifying feature is the presence of two prominent, parallel spinnerets that extend from the end of their abdomen, often visible from above. Hobo spiders do not have a violin-shaped marking on their back or distinct dark stripes on their cephalothorax.
Distinguishing Hobo Spiders from Look-Alikes
Differentiating hobo spiders from other similar-looking species can be challenging, often requiring microscopic examination for definitive identification. Coloration can be an unreliable characteristic. Several common spiders are frequently mistaken for hobo spiders, necessitating careful observation of specific features.
The giant house spider (Eratigena atrica) is often confused with the hobo spider, as both are funnel weavers. However, giant house spiders are larger and possess longer, more robust legs. Domestic house spiders (Tegenaria domestica) are smaller than hobo spiders and often exhibit a more patterned abdomen.
Wolf spiders (Family Lycosidae) are another group frequently mistaken for hobo spiders, but they have distinct differences. Wolf spiders are larger, ranging from 1 to 3 centimeters in body length, and have robust, hairy bodies. A primary distinguishing feature is their eye arrangement: two large anterior eyes, two large posterior eyes, and four smaller eyes in a row, differing from the hobo spider’s two horizontal rows of eight equally sized eyes. Unlike hobo spiders, wolf spiders are active hunters that do not construct webs to capture prey. Many wolf spider species also display more distinct markings and banding on their legs.
Hobo Spider Habitat and Web Structure
Hobo spiders inhabit outdoor environments in undisturbed areas. They favor locations such as fields, woodpiles, rock retaining walls, and tall grasses. These spiders also utilize foundation cracks and other sheltered spots around homes. While primarily outdoor dwellers, hobo spiders, particularly males searching for mates, may migrate indoors as cooler weather arrives, typically between August and October. Their physical characteristics make them poor climbers of smooth vertical surfaces, so they are usually found at ground level.
A distinctive characteristic of hobo spiders is their web, known as a “funnel web” or “sheet web with a funnel retreat.” This web is horizontal and sheet-like and is non-sticky. It features a tubular retreat at one end, where the spider waits in ambush. These webs are commonly constructed in corners, under objects, or near ground level, such as between bricks or beneath wood and stones. The web functions as a trap; when prey blunders onto the sheet, the hobo spider rushes out from its funnel retreat to capture it.
Next Steps After Identification
If you suspect you have identified a hobo spider, consulting a local entomologist or pest control professional can provide definitive confirmation, as microscopic examination is often required for precise identification. For safe removal, use a glass or jar to trap the spider and then slide a piece of paper underneath to contain it before releasing it outdoors, away from the home. Vacuuming is also an effective method for removing spiders, their webs, and egg sacs, with the contents immediately disposed of in a sealed bag outside.
Preventing hobo spiders from entering your home involves several practical steps. Sealing cracks and crevices around windows, doors, and your home’s foundation can eliminate entry points. Reducing clutter both indoors and outdoors, including woodpiles, debris, and tall grasses, removes potential hiding and breeding sites. Keeping vegetation trimmed and clear from the immediate vicinity of your home can also deter them. While hobo spiders were historically a concern, current scientific consensus indicates their bites are not as medically significant as once believed. The Centers for Disease Control and Prevention (CDC) no longer lists them among venomous species known to cause necrosis. They are not aggressive, and their species name “agrestis” means “of the field,” reflecting their preference for fields rather than aggressive behavior.