House spiders are a general group of arachnids that have adapted to live in human structures across the globe. These creatures are not a single species but rather several types of spiders routinely encountered indoors, often accidentally coming inside while seeking shelter or prey. Identifying these common house residents requires focusing on specific aspects of their anatomy. Visual characteristics—such as size, color, and unique body markings—are the most reliable tools for proper identification.
General Appearance: Size, Shape, and Color
All spiders share a basic body structure consisting of eight legs and two main body segments: the cephalothorax and the abdomen. The cephalothorax is the fused head and chest section, while the abdomen is the often-larger, rear section of the body. Most common house spiders are small to medium in size, with a body length typically falling between one-eighth and three-eighths of an inch.
The dominant color palette for spiders found indoors tends toward muted, earthy tones, allowing them to blend into shadowy corners and wood structures. These colors typically include various shades of brown, tan, light gray, and sometimes black. This combination of small body size and neutral coloring helps most species remain unseen in basements, attics, and wall voids.
Key Identification Markers: Eyes and Body Patterns
Moving past general color, the specific arrangement of a spider’s eyes is a definitive feature for identifying its family. Most spiders possess eight simple eyes, which are usually organized into two distinct rows of four. However, some families, such as the sac spiders or the recluse spiders, have six eyes arranged in three pairs.
The placement of these eyes—whether they are tightly clustered, widely spaced, or of noticeably different sizes—provides a crucial visual clue. Body patterns also offer excellent identification markers, often appearing on the abdomen. Common markings include chevron-like stripes (inverted V-shapes running down the back) or a distinct dark marking on the cephalothorax, such as the violin shape seen on the brown recluse. The texture of the exoskeleton, whether smooth or distinctly hairy, can also help narrow down the identification.
Profiles of Common Household Spiders
Cellar Spider
Cellar spiders, often mistakenly called “daddy longlegs,” are immediately recognizable by their extremely long, thin, and delicate legs relative to their body size. Their small, oval-shaped body is usually a pale yellow, tan, or light gray color. The legs can span up to four inches across, making the spider appear much larger than its tiny body.
These spiders typically have eight eyes, though some species may have six, and they are often found hanging upside down in their loose, irregular webs. Their slender legs and small, indistinctly marked body differentiate them from other spiders with shorter, stouter limbs.
American House Spider
The American house spider, also known as the common house spider, is a cobweb weaver characterized by a relatively large, globular abdomen and a smaller cephalothorax. Their coloring is highly variable, ranging from a grayish-white to a dull brown, often with a mottled or speckled appearance. The abdomen frequently displays chevron-like markings or faint dark spots.
Females are slightly larger than males, with a body length often exceeding a quarter of an inch. The legs are generally brown or yellow-brown and may have dark rings, appearing longer and thinner than those of a wolf spider but shorter than those of a cellar spider. This species is the classic “messy web” builder often seen in the corners of rooms.
Yellow Sac Spider
The yellow sac spider has a distinctive pale coloration, usually appearing light yellow, beige, or sometimes with a faint hint of green. This species is a hunting spider, meaning its legs are more robust and adapted for running than for web-building. Their body is oval-shaped, typically measuring about a quarter to three-eighths of an inch long.
A key visual trait is the presence of darker, sometimes brownish, feet (tarsi) on their otherwise light-colored legs. They lack the striking patterns of other species, presenting a fairly uniform color across the cephalothorax and abdomen. They are often found creating small, silken, sac-like retreats where a wall meets a ceiling or another surface.
Domestic House Spider
The domestic house spider, which belongs to the funnel-web family, is generally a larger, faster-moving species often found indoors. Its body shape is more flattened and elongated compared to the rounded shape of a cobweb weaver. The coloration is typically a mix of dark browns, tans, and grays.
The cephalothorax often features two distinct dark stripes running lengthwise, while the abdomen may display faint, subtle markings or chevrons. This spider is distinguished by its long legs, often covered in fine hairs. The legs are typically quite long, with the fourth pair sometimes being the longest, giving the spider a slightly backward-slanting posture.