No, you shouldn’t kill daddy long legs. They’re harmless to humans, and in most cases, they’re actively helpful by eating other pests in your home. But “daddy long legs” actually refers to three completely different creatures depending on where you live, so it’s worth knowing which one you’re dealing with.
Which “Daddy Long Legs” Are You Looking At?
Three very different arthropods share this nickname, and none of them pose any threat to you.
Cellar spiders are the most common one people encounter indoors. They’re true spiders with two distinct body segments, eight eyes, and messy, tangled webs in corners and basements. These are the ones most likely prompting your search.
Harvestmen look like spiders but aren’t. Their body appears to be a single round segment because the two halves are fused together. They have only two eyes, produce no silk, build no webs, and carry no venom at all.
Crane flies are insects that look like oversized mosquitoes. They have six legs and wings, don’t bite, don’t sting, and are basically just clumsy fliers that bumble into your house through open doors.
None of these three can hurt you. Not one.
The “Most Venomous Spider” Myth
You’ve probably heard the claim that daddy long legs are the most venomous spiders in the world but their fangs are too small to bite humans. This is false on every count.
Cellar spiders can bite humans. Their fangs are structurally similar to those of the brown recluse. But their venom is weak. Rick Vetter, an arachnologist at UC Riverside, has noted that no published research shows cellar spider venom causing any toxic effect in people. One scientist who allowed himself to be bitten reported a small dark mark that disappeared in a day or two.
A 2004 episode of MythBusters, later documented in a 2019 study, directly compared cellar spider venom to black widow venom by injecting mice with both. The black widow venom was far more potent. Cellar spider venom simply isn’t dangerous.
As for harvestmen, they don’t have venom glands at all. And crane flies have no biting mouthparts. So regardless of which daddy long legs you’re dealing with, you have nothing to worry about.
Why Cellar Spiders Are Worth Keeping Around
Cellar spiders are surprisingly effective pest controllers. They eat other small insects, and they regularly take down prey much larger than themselves, including wolf spiders and crane flies. In parts of the world where dangerous spiders live in and around homes, cellar spiders actively hunt them.
Their hunting technique is remarkable. A cellar spider captures larger, more dangerous spiders by casting long strands of silk from a safe distance, binding the prey before it can fight back. Some cellar spiders will even invade another spider’s web, vibrate the silk to mimic a trapped insect, and then eat the host spider when it comes to investigate. They’re small but clever predators that tip the balance away from species you’d rather not have in your house.
They typically stay put in one corner, don’t wander around, and don’t bother people. They’re slow movers that pose zero practical nuisance beyond their webs looking a bit untidy.
If You Really Don’t Want Them Inside
If the webs bother you or you’d rather not share your space, relocating is better than killing. The simplest method is the glass-and-paper technique: place a cup over the spider, slide a piece of paper underneath, and carry it to a new spot.
Where you put it matters, though. Many cellar spiders have adapted to indoor life over generations. If you toss one outside in a climate it’s not suited to, it may not survive. A better option is relocating it to a part of your home where you won’t notice it: a garage, basement corner, or shed. If you’d rather put it outside, it may find suitable habitat, but there’s no guarantee.
Reducing Their Numbers Without Killing
If you’re seeing a lot of cellar spiders, the real issue is usually moisture. These spiders prefer damp, dark, undisturbed spaces. Fix leaky pipes, improve drainage around your foundation, and run a dehumidifier in your basement or crawl space. Better ventilation alone can make a noticeable difference.
Regular cleaning is the other big lever. Vacuuming or sweeping away webs and egg sacs on a consistent schedule disrupts their ability to reproduce and feed. Each female lays a few dozen eggs at a time, wrapped in silk for protection, so removing those egg sacs directly limits population growth.
Decluttering also helps. Cellar spiders thrive in spaces full of boxes, old furniture, and undisturbed piles of stuff. Seal storage items in containers, clear debris away from your foundation, and trim any vegetation touching the outside of your house so spiders can’t use plants as a bridge indoors. Sealing cracks with caulk, filling larger gaps with expanding foam, and adding weather stripping around doors and windows cuts off their entry points.
These steps reduce not just cellar spiders but the insects they feed on, which means fewer reasons for any spider to set up shop in your home.