If you’ve spotted a spider that looks almost see-through, you’re likely looking at one of a few common household species. Translucent or “clear” spiders are usually cellar spiders, yellow sac spiders, or ghost spiders, all of which thrive indoors and share that pale, glassy appearance that makes them hard to identify at a glance. The good news: none of them pose a serious medical threat.
Cellar Spiders
Cellar spiders are the most common translucent spider people encounter indoors. They have extremely long, thin legs and a small, pale body that can look nearly transparent under certain lighting. You’ll find them in dark corners of basements, crawl spaces, and garages, hanging upside down in loose, messy webs that seem to spread in every direction.
These are the spiders behind the popular myth that “daddy longlegs are the most venomous spider in the world but can’t bite you.” According to researchers at the University of California, Riverside, there is no scientific basis for this claim. No pholcid spider (the cellar spider family) has ever been documented biting a human and causing a harmful reaction, and no toxicology study has tested their venom on any mammalian system. They do have short fangs with a pincer-like structure, but their bite musculature is weak compared to hunting spiders. In practical terms, cellar spiders are completely harmless to people.
Yellow Sac Spiders
Yellow sac spiders are the other likely candidate when someone spots a “clear” spider indoors. They’re small, typically 4 to 10 millimeters in body length, with a light yellow to cream-colored body. One common species has a faint greenish tinge on its abdomen. Both have dark brown tips on their legs and jaws, and a subtle darker stripe running down the top of the abdomen, details you’d only notice up close.
Unlike cellar spiders, yellow sac spiders don’t build traditional webs. They’re active hunters that roam walls and ceilings at night looking for prey. During the day, they retreat into a small, flattened silk pouch (their “sac”) tucked into an upper corner of a room or a crack in the wall. They’re the most common spider found wandering through homes in the fall, and their pale color against a white ceiling gives them that transparent, hard-to-see quality.
Yellow sac spiders can bite if pressed against skin, such as when they crawl into clothing or bedding. A bite typically produces localized redness, mild swelling, and a stinging sensation similar to a bee sting. Older sources sometimes linked these spiders to necrotic (tissue-destroying) wounds, but more recent evaluations suggest those cases were likely misdiagnosed brown recluse bites or bacterial infections. Most yellow sac spider bites resolve on their own within a few days.
Ghost Spiders and Other Pale Species
Ghost spiders are a less well-known group, but they share the same translucent look. They’re small, fast-moving hunters with pale, almost colorless bodies and relatively long legs. They don’t build webs and are most active at night, which means you’ll usually spot one darting across a wall or floor after dark. They’re harmless and rarely bite.
Some juvenile spiders of various species also look translucent simply because they haven’t fully developed their adult pigmentation. A young wolf spider or jumping spider can appear nearly clear before darkening with age. If the spider you saw was very small (under 3 millimeters), it may just be an immature specimen of a common species rather than a distinct “clear” type.
How to Tell Them Apart
- Long, wobbly legs and a messy web in a dark corner: cellar spider.
- Small, pale yellow body wandering a wall or ceiling at night, no web: yellow sac spider. Look for a silk retreat in the corner of the room.
- Very small, fast, no web, colorless body: ghost spider or a juvenile of another species.
Keeping Clear Spiders Out of Your Home
Regular cleaning is the single most effective strategy. Vacuuming corners, ceilings, and window frames removes spiders, their webs, and their egg sacs. Destroying egg sacs matters more than killing individual spiders, since each sac can contain hundreds of young.
To prevent them from getting inside in the first place, install tight-fitting window screens and door sweeps. Trim any shrubs, vines, or tree branches that touch the exterior of your house, since these act as bridges for spiders to reach walls and find gaps. Seal cracks around foundation vents, door thresholds, and the bottom edges of siding.
Outdoor lighting also plays a role. Standard white bulbs attract night-flying insects, which in turn attract spiders. Switching to yellow or sodium vapor bulbs at exterior entrances reduces the insect activity that draws spiders close to your home. If spider activity is persistent, a perimeter spray applied around the foundation, garage entrance, and crawl space openings can reduce new arrivals, though it typically needs to be reapplied every month or two during warmer seasons.