The most effective way to keep daddy long legs out of your home is a combination of sealing entry points, reducing clutter, and eliminating the insects they feed on. Spraying pesticides is largely ineffective against spiders, so physical exclusion and environmental changes do the heavy lifting.
Before diving into solutions, it helps to know what you’re actually dealing with. “Daddy long legs” refers to three completely different creatures depending on where you live: cellar spiders (the ones spinning messy webs in ceiling corners), harvestmen (the outdoor arachnids with a compact body and no web), and crane flies (the gangly flying insects). Most people searching for this are dealing with cellar spiders indoors, so that’s the main focus here.
Seal the Gaps They Use to Get Inside
Spiders don’t need much space. A gap of just 1/16 of an inch under a door is enough for them to slip through. The single most impactful thing you can do is close off these entry points throughout your home.
Start with exterior doors. Install door sweeps at the base and lie on the floor to check for light filtering underneath. If you can see light, spiders can get in. Garage doors need a rubber bottom seal (vinyl cracks and fails in cold weather). Sliding glass doors often have gaps along the bottom track that you can fill with half-inch to three-quarter-inch foam weatherstripping.
Next, inspect where utilities enter your home. Pipes, wires, outdoor faucets, gas meters, dryer vents, and cable lines all create small openings in your foundation and siding. Plug these with silicone caulk, expanding foam, steel wool, or copper mesh. For cracks around windows, doors, and fascia boards, acrylic latex caulk works well because it’s paintable and cleans up with water. Finally, check every window and door screen for tears or gaps and repair them.
Remove What Attracts Them
Cellar spiders go where the food is. They eat mosquitoes, flies, moths, roaches, silverfish, gnats, and even other spiders. If your home has a steady supply of small insects, it’s essentially an open buffet. Reducing that insect population is one of the best long-term strategies.
Outdoor lighting is a major insect magnet. Switching to yellow or sodium vapor bulbs at exterior entrances draws far fewer night-flying insects to your doorways, which in turn gives spiders less reason to set up nearby. Inside, keep food sealed, take trash out regularly, and fix any moisture problems like leaky pipes or poor ventilation in bathrooms. These steps cut down on the flies, gnats, and roaches that cellar spiders depend on.
Clean and Declutter Regularly
Cellar spiders strongly prefer quiet, undisturbed spaces: closets, basements, attics, garages, and storage areas. The less cluttered these spots are, the less hospitable they become. Regular, thorough cleaning is consistently cited by entomologists as the single best way to eliminate spiders and prevent their return.
A vacuum cleaner or broom removes spiders, their webs, and their egg sacs in one pass. Pay special attention to ceiling corners, behind furniture, and along baseboards. Outside, move firewood, stacked materials, and debris away from your foundation. Trim back shrubs, vines, and tree branches that touch the house, since these act as bridges spiders use to reach your walls and find their way inside.
Peppermint Oil and Other Natural Repellents
Essential oils show up constantly in home remedies, but the science is mixed. In controlled choice tests, peppermint oil and chestnut repelled two out of three spider species more than 75 percent of the time. Lemon oil, despite being the most commonly recommended option online, had no significant repellent effect on any species tested.
If you want to try peppermint oil, mix 15 to 20 drops with water in a spray bottle and apply it around windowsills, door frames, and corners where you’ve seen webs. The effect fades as the scent dissipates, so you’ll need to reapply every few days. It’s a reasonable supplement to other methods, but don’t rely on it as your only line of defense.
Diatomaceous Earth for Persistent Problems
Food-grade diatomaceous earth (DE) is a fine powder made from fossilized algae. At a microscopic level, the particles have sharp edges that damage a spider’s outer coating, causing it to lose moisture and die from dehydration. It works, but only when spiders walk directly through it.
Apply a thin, barely visible layer along baseboards, in wall voids, around outlets, in closets, and in storage areas. The key is keeping it light. A heavy layer actually discourages spiders from walking through it, defeating the purpose. A powder duster helps you get DE into tight or awkward spaces. Leave the application in place for about a week, then clean it up and reapply if needed. Wear gloves and a dust mask during cleanup to avoid breathing in the fine particles. Outdoors, DE loses effectiveness when it gets wet, so you’ll need to reapply after rain.
Why Pesticide Sprays Don’t Work Well
It’s tempting to reach for a can of bug spray, but spiders aren’t insects, and residual insecticides were formulated for insects. Spiders don’t absorb these chemicals through their feet the way ants or roaches do. A direct spray will kill a spider on contact, but the residue left behind on surfaces does very little to prevent new ones from moving in. Spider egg sacs are also relatively impervious to pesticides, so even a thorough spray can leave the next generation untouched.
They’re Harmless (and Useful)
The old claim that daddy long legs are “the most venomous spider in the world but can’t bite you” is a myth on every level. Harvestmen don’t have venom glands at all. Cellar spiders do have venom, but there’s no documented case of a cellar spider bite causing any harmful reaction in a human, and no toxicological studies support the idea that their venom is especially dangerous. Their fangs are short and may lack the muscle strength to penetrate skin in the first place.
Cellar spiders are actually effective pest control agents. They prey on mosquitoes, flies, roaches, and silverfish. They’ve even been documented killing black widows, brown recluses, and hobo spiders by wrapping them in silk from a safe distance before the larger spider can strike. If you can tolerate a few in your basement or garage, they’re quietly working in your favor. But if you’d rather not share your living space with them, the combination of sealing gaps, reducing clutter, cutting off their food supply, and regular cleaning will keep their numbers low without needing chemicals.