The hobo spider, scientifically known as Eratigena agrestis, often sparks curiosity and concern due to its size and appearance. Understanding its dimensions is a common starting point for identification, helping differentiate it from other spiders.
Measuring a Hobo Spider’s Size
Hobo spiders exhibit variations in size between sexes. Females generally have a larger body, measuring 9.5 to 16.5 millimeters (approximately 3/8 to 5/8 inches) in body length. Males are slightly smaller, ranging from 7 to 13.5 millimeters (about 9/32 to 9/16 inches). These measurements exclude the legs, which contribute to the spider’s overall perceived size.
Including legs, hobo spiders can reach a leg span of up to 2 inches (5.08 centimeters). The male’s leg span can sometimes exceed that of the female, even with a smaller body, as they are often more slender with proportionally longer limbs.
Beyond Just Size: Other Identifying Features
Hobo spiders possess several distinct physical characteristics that aid in their identification. Their coloration typically ranges from light to medium brown. The cephalothorax, the fused head and thorax, is usually brown with diffuse, indistinct darker markings.
A more telling feature is the pattern on their abdomen, which often displays a series of chevron (V-shaped) markings pointing towards the head. While these patterns can sometimes be faint or irregular, particularly in adult specimens, they are a common indicator. Unlike many other spider species, hobo spiders generally lack distinct dark bands or rings on their legs, which are uniformly colored.
Examining the sternum, the underside of the cephalothorax, can provide clues; hobo spiders typically have a light stripe running down its middle and lack the three or four pairs of light spots found on some related species. Male hobo spiders also have noticeably enlarged pedipalps near their mouth, often described as resembling small boxing gloves, which are used in reproduction. Their legs, though long, are covered in fine, feather-like hairs known as plumose setae.
Comparing Hobo Spiders to Look-Alikes
Many spiders are frequently mistaken for hobo spiders due to similar size or general brown coloration. Two common look-alikes are the giant house spider (Eratigena atrica) and wolf spiders (Lycosidae family). Differentiating them requires attention to specific details beyond just overall size.
Giant house spiders, while similar in appearance and often larger than hobo spiders, can be distinguished by distinct dark bands on their legs, a feature absent in hobo spiders. Giant house spiders may also have a more pronounced leaf-shaped pattern on their abdomen. Both species construct funnel-shaped webs, but the hobo spider’s web is typically non-sticky and trampoline-like.
Wolf spiders, which are also fast-moving and brown, are another common source of confusion. The most reliable way to tell them apart is by examining their eye arrangement: wolf spiders have a distinctive pattern of three rows of eyes, including two large, forward-facing eyes, whereas hobo spiders have eight eyes arranged in two nearly straight rows. Wolf spiders are also generally hairier and are active hunters, rarely building webs for prey capture.
Where Hobo Spiders Are Found
Hobo spiders are primarily found in western North America, having been introduced from Europe. Their established range includes the Pacific Northwest, specifically British Columbia, Washington, and Oregon. This distribution has expanded eastward into states like Montana, Wyoming, Colorado, Nevada, and northern Utah.
These spiders commonly inhabit sheltered outdoor areas, preferring locations such as woodpiles, rock retaining walls, and tall grasses where they can construct their characteristic funnel-shaped webs. Indoors, hobo spiders are often encountered in basements, crawl spaces, garages, and window wells, as they favor dark, damp, and secluded environments. Since they are not skilled climbers, they are typically found at ground level and may become trapped in sinks or bathtubs.