You can kill and repel spiders using a combination of cleaning, re-organizing, and spraying with natural or man-made sprays, or chemical treatment by a professional exterminator.
Clearing out the spiders from your basement will take a little more work and a combination of cleaning, organizing, effective spider spray, and seasonal uncluttering.
Maybe fall comes and you head down to your basement for your first load of firewood or perhaps summer arrives, and you need the inner tubes and beach balls from the cellar. Either way, as you make your way to your intended target you walk right into a spider web, or a massive arachnid runs across the floor. You discover the icky, hard way that spiders invaded your basement. Your first thought might be to grab a can of bug spray and spray every corner but that only addresses the immediate problem. You won’t create a spider-free environment that way.
Addressing the situation to get rid of the existing spiders and prevent new spiders from developing requires combining the long-term and short-term approaches. You’ll need to gain access to the walls and crevices, floor and ceiling edges in order to clean and spray. You’ll also need access to this area to reorganize and declutter.
12 Steps to Getting Rid of Spiders in Your Basement
Here’s the order you need to complete these items in for the best results. Whether you want to address the spider problem this minute or over the long-term, you’ll need to do each of these.
Creating Treatment Space
Pull everything away from the walls and place it in the center of the room. You’ll need to go through it and get rid of the things you do not need. You could wait to do this until after you treat the walls and ceiling, but spiders like boxes, so you will probably find and get rid of some spiders in the process of going through boxes. If one gets away now, you still have the walls and ceiling treatments to do later, and it will die then.
Re-box the items you want to keep in clear, plastic bins with snap-shut lids. This lets you see what a bin holds without needing to open the top lid. The lid keeps the spiders from entering the bin the way they can in a cardboard box.
Cleaning Out Cobwebs
Using a broom, sweep the ceiling edges, corners, walls, and flooring edges. Carefully clean any crevices with the broom first. You need to knock down all of their webs, so no spider web remains.
Spray or pour a spider-killing substance into the crevices and foundation gaps. You could use a natural substance like diatomaceous earth or vinegar, or you can use a store-bought mixture like Miss Muffet’s Revenge or Raid. Either way, give it at least one hour to take effect, or the time noted on the product packaging.
Using a spackle that matches the wall, ceiling, or floor, patch the crevices, filling them completely. The idea is to take away the spiders’ hiding places. Use caulk under your baseboards and fill any flooring gaps. By patching the cracks and crannies, you not only block the spiders’ nesting point but also improve the health of your home and its structure. Once the spackle dries, paint over it using a color that matches the paint.
Also, caulk around vents, pipes, and any other areas that pass through the walls to the great outdoors. This shuts off their access to your home. Also, caulk around windows and doors.
Install shelving at least one foot above the floor sturdy enough to hold the items you re-boxed in the plastic bins. Bugs like the ground, so spiders like the ground because they eat bugs. This reduces the number of bugs and spiders with access to your stuff.
Re-organize Items on Shelves
Store your re-boxed items on the shelving. Spray the area completely, including the bins themselves.
Move any woodpile you have in the basement outdoors, as far from the home as possible. Bugs love to hide in wood piles, so spiders also love them.
Use Ultrasonic Devices
Plugin one or two ultrasonic devices in the basement. These handy gadgets produce a high-frequency noise that humans cannot detect but which bugs, spiders, and mice detest. It drives them away from the home.
Patch Outside Foundation Cracks
On the outside of the home, patch foundation cracks. By patching both sides of the wall, you close their entry points and trap any spiders inside your walls that you might have missed with the bug/spider spray. Once cut off from their exit points, these critters have no food source and die.
Call a Professional Exterminator
Call a professional exterminator if you still see spiders in your home, especially your basement. You should have eradicated them all by now so if you see more of them, you need an exterminator.
You do not have to kill the spiders living in your basement to get rid of them. You can trap them instead. Many types of traps exist for this purpose including those similar to humane mouse traps, glue traps, flypaper, etc. When the spider steps on these items, its leg becomes stuck in the glue. You can take the trap outdoors and use a long stick to gently un-stick the spider’s leg. You let it out far from your home and both the spider and you stay happy.
How to Get Rid of Spiders in the Basement Naturally
Perhaps you are okay with killing the spiders, but you want to use only environmentally friendly products. You can kill spiders without using any harsh chemicals. Avail yourself of one of the many options below.
Get a cat: This option probably provides the most fun since you get a sweet pet out of the deal, plus spider repellent that works. Felines love bugs and spiders as snacks. As an added bonus, your home won’t develop a mouse problem either. Plus, frisky felines make great fur friends. They enjoy human companionship but don’t take it too far. They enjoy mousing and bugging, and you can simply let your feline wander the basement one day per week. Your bug and spider problem will disappear in no time. You will still need to feed your cat each day a bit of wet or dry food, so they get the appropriate amount of taurine.
Diatomaceous earth: Made from the fossilized sediment of algae found in water bodies, this powder provides a soft, porous dirt that you can spread safely indoors and outdoors. Its tiny, ultra-sharp particles cut into the exoskeleton of arachnids and insects. As soon as they step on it, it begins working. They die because the silica in the dirt sticks to them after it cuts into them. It absorbs the water and oil in their bodies, drying them out. They die from dehydration. The dirt doesn’t harm humans or typical house pets though.
Vacuuming: Use a large vacuum with long attachments that let you vacuum ceilings and corners. These frequently are used to vacuum drapes, as well. You can use the vacuum cleaner to reach dark spots, corners of closets, behind the washer and dryer, etc. This method lets you suck them right up into the vacuum cleaner’s dirt-trap. They die. Just in case one survived, instead of emptying the dirt trap indoors, take your trash can to the curb and empty it directly in the bin at the curb.
How to Get Rid of Spiders in Basement Naturally
Many methods of natural spider repellent exist. These essentially consist of substances that spiders hate. Rather than kill the spiders, you deter spiders. The upside of using this method is that it works effectively on cellar spiders and spiders in other areas of the house. Any of the essential oils smell awful to spiders but lovely to humans.
Essential oils: You can mix many essential oils with water to form a spray that you can use in the basement to drive away spiders. Spiders don’t have noses like humans. Instead, they use their legs to both taste and smell everything. They seriously dislike any strong smell. You might love the smell of peppermint, citrus oils, such as lime, lemon, orange, eucalyptus, citronella, cedarwood, tea tree, or lavender oils, however, spiders abhor it. There isn’t one of those essential oil smells that they enjoy but they hate peppermint the most.
They definitely do not want it on their legs, so they avoid walking through areas that smell strongly of any of those essential oils. This option does not kill them. It only repels them. Rather than use the oils straight, which could become quite expensive, you mix them with about a cup of warm water and one squirt of dish soap.
Plant eucalyptus trees.: If you plant a few of these types of trees in your front and backyards, the spiders will detest your yard which is how they reach your house. They’ll just basically run the other way on their little eight legs.
Plant potted lavender: Plant a few pots of lavender and keep them on the front and back porches or on your deck. Spiders also dislike the smell of lavender.
White vinegar: Mix white vinegar and water together in a spray bottle. Spray all of the corners, baseboards, etc. They dislike this pungent scent and won’t come near it either.
What Methods Do Exterminators Use to Kill Spiders?
Sometimes, your best efforts can’t beat the pesky arachnids who have invaded your home. If you find evidence of either black widow spiders or brown recluse spiders, you definitely need to have an exterminator visit. Both types carry deadly venom. You would need to visit a hospital for treatment within 24 to 72 hours of a bite from either. The black spiders of this deadly pair proves more deadly. However, if the bite of the brown recluse goes untreated within the first 72 hours, it can result in the loss of a limb.
Other spiders prove much more benign. They dine on bugs and other pests, so they keep your house free of bugs. Of course, if you have a phobia about them that doesn’t matter much. You probably want them, and the bugs gone. The sprays used by exterminators depend on the local ordinances. Some areas require environmentally friendly sprays, while others allow a wider array of chemicals.
Typically, these chemicals include deltamethrin (the best spider spray for basement areas), cypermethrin, bifenthrin, lambda-cyhalothrin, and cyfluthrin. These powerful chemicals can kill even the pesky brown recluse, also called the violin spider.
Bees, fish, and other marine life also die when exposed to deltamethrin, prompting states including Alaska, Connecticut, New York, and Rhode Island to illegalize its use. This dust insecticide proves low toxicity to birds and mammals.
Some countries, including the United Kingdom, have banned cypermethrin because not only do bees, fish, insects, and aquatic invertebrates find it seriously toxic, humans find it slightly to moderately toxic. Another dust insecticide, it kills the deadly spiders, but quite a bit else, too.
Cyfluthrin paralyzes the nervous system of spiders. It also kills insects and other invertebrates. Toxic to marine life, this aerosol causes skin and eye irritation in humans.
Bifenthrin works in a similar manner to cyfluthrin. This water-insoluble with a half-life of up to four months in the soil does kill the spiders. It also kills other invertebrates. Exterminators in the European Union can no longer use this substance since it was proved highly toxic to beneficial insects and aquatic life.
Each of these chemical options proves detrimental to more than just spiders. If you must have your home treated with any of the above substances, you should vacate it for a few days, taking your pets with you. That will let the worst of the chemicals pass through the air without harming you. Spiders don’t die easily, so some of the chemicals used to get rid of egregious infestations sound pretty horrifying. They work though.
Considerations of Doing It Yourself vs. Hiring a Professional
Part of the above 12-step plan to rid yourself of spiders you cannot avoid. That is the part about pulling everything away from the wall and cleaning. You also have to go through the boxes because keeping boxes that spiders live inside won’t do you any good towards getting rid of them. You’ll still need to clean and re-organize.
You might want the spiders gone immediately, which favors the exterminators. On the other hand, if you have a medical condition, such as asthma, or another person in your home does, you may want to leave that to the last resort.
You could research which exterminator in your local area your friends and family use, then phone them to ask a few questions. Find out what they use and search for it on your computer while you speak with them. This lets you see any warnings about the chemicals and ask them questions about personal protection and what you should do with your pets while they treat the basement and the rest of the house.
Reaching out to ask specific questions can help you make a decision and prepare for having the house treated. Recognize that if you have the basement treated, you need to also have the rest of your home treated for spiders. Most of the chemicals only kill existing spiders but not their eggs. That means once the air proverbially clears, new spiders move in or are born. If your basement seems unsuitable, the rest of your house will look really good to them. They’ll simply move up a level and find a nice, dark closet or hid under your bed.
Essentially, keep a clean, uncluttered home that gets regularly treated with spider bane, such as the essential oils mixture or diatomaceous earth to keep spiders away. The only other option remains the regular treatment of your basement and house with the harsh chemicals mentioned.
Deciding between natural methods, do-it-yourself chemical sprays, or a professional exterminator, takes some research. Your local exterminator may use a less horrifying chemical such as deltamethrin. While a serious chemical, it does the least damage to other animals and to humans.
The best method remains to go through the 12-step method to rid yourself of most of the spiders, if not all. After doing so, if you still see arachnids moseying around your basement, call an exterminator. You can work with them to choose a chemical that works effectively but doesn’t cause as much harm as the ones that have been banned in the UK, EU and some US states. While the simple boric acid method won’t work for spiders, you can find relatively effective methods of deterring these pests from entering your home and setting up their own digs.
You might need to try the natural treatments more than once. If you really need your home clear of spiders quickly though, the professional exterminator can help you quickly.