This non-native species, also called the aggressive house spider, has a reputation for packing a punch with its bite, though the jury’s still out on the true effects of its venom. The Oregon Department of Agriculture reports that it is not considered dangerous in its native haunts in Europe, and that the “aggressive” moniker stems from its Latin name, not its true behavior (see Reference 1). Regardless, it’s a difficult spider to accurately identify without a microscope, drably colored and similar in appearance to related species like the giant and domestic house spiders--larger and smaller, respectively, than the hobo, which may be better than an inch across (see Reference 3).
Species of wolf spider may occasionally be encountered in Oregon homes, especially in the fall. They may be quite large, but are not normally aggressive. A pattern of stripes on their back, often resembling the Union Jack design, helps distinguish them from similarly sized house spiders.
Yellow Sac Spider
These small spiders--up to an inch across, counting the legs--may enter homes and reveal themselves through the pale, silky sacs they sometimes construct for daytime shelter, often encountered in corner and windowsill nooks. Yellow sac spiders, usually yellow or tawny in hue, mainly hunt under cover of darkness. (See references 1,3).
Jumping spiders, sometimes known as zebra spiders, are well distributed, common hunters of diminutive proportion and athletic nature. Well under an inch in length, they are frequently encountered outside--on walls, walkways and shrubs--but may enter homes as well, where they may be spotted jumping and jerking haltingly in pursuit of tiny prey.
This wispy spider has very long legs and a narrow body, and builds its airy webs in high corners and other tucked-away places. The cellar spider often appears almost crumpled in its refuge, but will shake the strands of its web if disturbed.
The black widow, the most venomous of Oregon’s spiders, is a very small inhabitant of dark, quiet places like basements, sheds and the innards of woodpiles. Females are, as in most spider species, larger than males and distinguished by their bulbous, black body, patterned with a red hourglass on the underside. The Oregon Department of Agriculture notes that black widows are notably more common in southwestern and eastern Oregon, though they can be encountered anywhere in the state (see Reference 1).