How to Get Rid of Black Widow Spiders

Co-authored by Chris Parker

Last Updated: July 7, 2022 References Approved

Spiders can be very useful in controlling the populations of harmful insects in your garden—and most of the spiders you see around your home are harmless. Unfortunately, the bite of a black widow spider can be very painful and even deadly, which makes them a dangerous pest and not a creature you want around your home. There are several ways to eliminate Black Widow spiders from your house and garden and to prevent them from returning. Exercise caution and follow the correct safety procedures.

Part 1

Part 1 of 3:

Identifying Black Widow Spiders

1
Recognize a black widow spider. Black widow spiders are found across the U.S and Canada, and in other temperate regions around the world. They are the most venomous spiders in North America. The female is the easiest to recognize -- and the most dangerous. She is coal-black, with a spherical abdomen and a red hourglass-shaped mark on her belly. Her body is approximately half an inch long, but she has a total length of 1.5 inches (3.8 cm) with her legs extended.
- The male is about half the size of the female and is brown or grey. He usually has several red dots on his abdomen and may have a yellow or red band across his back. Male black widow spiders are not venomous.
- Young black widows, known as spiderlings, are white or yellow-white when they first hatch. They become darker as they grow. They may have yellow or red patches across their backs, resembling the adult male. It is impossible to tell male and female spiderlings apart. At this stage, both are harmless to humans.
2
Know its habits. The black widow spider is timid and reclusive, preferring to make its home in dark, protected areas, such as in boxes, among firewood and under ledges. It is nocturnal, actively hunting at night.
- The black widow spider's web is usually located within a foot of the ground. It is slightly erratic in appearance and made with stronger silk than most other spider webs. The web is used to catch prey and to hang the female's cocoon of eggs.
- Black widows are usually found in dark corners of the house or around the edges of a yard or garage where their webs will have a lesser chance of being disturbed. They may also be found under vehicles, even those that are being driven periodically. Check for webs near the tires, or under/around the engine.
- Black Widows are territorial, so their webs are often spaced about a foot apart.
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3
Understand the dangers. Female Black Widow spiders have very powerful venom -- in fact, it is said to be15 times stronger than that of a rattlesnake. The venom is a neurotoxin. Symptoms include muscle aches, abdominal pain, breathing difficulties and nausea. The majority of Black Widow bites are easily treated. However, if medical treatment cannot be administered on time, a Black Widow bite can lead to convulsions and death.
- Black Widow spiders are not aggressive and will only bite as a defense mechanism. Most bites occur when the spider is accidentally disturbed or injured, and feels threatened.
- Small children, the elderly and the infirm are much more susceptible to adverse reactions when bitten by a Black Widow. Medical treatment should be sought immediately.
4
Watch out for Brown Recluse spiders too. Another venomous spider which is slightly more common than the Black Widow is the Brown Recluse spider. These are harder to identify because they look like many other spider species, ranging in color from dark cream to brown. They are similar in size to the black widow and have a dark violin shaped mark on their back.
- The venom of the Brown Recluse spider is not as strong as the Black Widow's, but their bite can lead to death.
- The methods for getting rid of Brown Recluse spiders are the same as for the Black Widow, so you can target both species at once.

Part 2

Part 2 of 3:

Hunting and Killing Black Widow Spiders

1
Locate as many spider webs as you can during the day. Black Widow spiders are nocturnal, so they are inactive during the day. Daytime is the best time to locate all existing webs, so you can come back and kill the spiders once darkness falls. Look for the webs in dark, sheltered areas that are usually left undisturbed.
- Indoors, look for webs in dark corners of closets, under the bed and in cluttered areas of the basement and attic. Outdoors, look for the webs under window ledges and door frames, in piles of firewood or stacked lumber and in close-growing vegetation.
- Black Widow webs are disorganized and erratic looking. They are slightly funnel-shaped, giving the female Black widow a convenient place to hide during the day. Never intentionally disturb a web without protective clothing and a method of killing the spider.
- Make a note of the location of each web, so you will be able to return to it later.
2
Clean the area thoroughly. The easiest way to get rid of spiders is to physically remove them from the environment. Vacuum and dust thoroughly, including along your baseboards and in the clutter of the rooms. Also, clear out any clutter that could be hiding spiders or spiderwebs.^{[1]
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Expert Source

Chris Parker
Pest Control Specialist
Expert Interview. 21 April 2021.}
3
Try using dust applications and liquid spot treatments. Once you know the locations of the webs, there are a couple of things you can try to eliminate the spiders without actively killing them. Get your hands on a dust or liquid insecticide which you can spray or sprinkle on the webs and surrounding areas. These will kill the existing spiders upon contact, while also preventing new spiders from moving in.
- Dust applications are best for out-of-the-way places where the dust won't be disturbed by anyone but the spiders. This includes attics, basements and crawl spaces. It can also be applied to wall voids, using a hand duster. Products such as Drione Dust and Delta Dust Insecticide are recommended.
- Liquid spot treatments are usually purchased in powder form, which is then mixed with water to form a residual spray. This works best under and behind furniture, under beds, in storage spaces and any dark corners. Products such as Demon WP Insecticide and Cynoff EC are recommended.
- Even though these products are very effective, they are not guaranteed to kill all of the spiders, so they are best used in combination with more active methods of elimination and to prevent new spiders from coming back.
4
Return to the webs at night to kill the spiders. The most surefire way to kill the Black Widow spiders is to return to their webs at night -- armed with your weapon of choice -- and eliminate them yourself. It doesn't have to be the middle of the night, once the sun sets the spiders will be active and easy to find. Make sure to bring a powerful flashlight and to wear protective clothing, such as thick gloves and boots, as the spiders can be very quick when under threat and you want to expose as little skin as possible. Here are the best methods of killing the spiders:
- Kill the spiders with insecticide. Using a non-residual spray insecticide is one of the quickest and easiest ways of killing Black Widow spiders. The spray must come in direct contact with the live spider, at which point it will quickly stun and kill it. These sprays are safe to use and will not leave harmful residues behind.
- Squash the spiders. A more hands-on method of killing the spider is just to squash it. It may not be elegant but it's certainly effective. Just make sure to use a stick or shoe to avoid coming in too close contact with the spider, in case you miss. Black Widows may run toward you rather than away from you when under attack.
- Vacuum the spiders. A vacuum with a hose attachment can be used to quickly suck up the spiders without the need to get too close. This method is obviously best for indoor webs and can be very effective for catching spiders in hard-to-reach places, as the suction will pull them out. Once you have vacuumed the spiders, take the vacuum bag out immediately, place it in a securely tied garbage bag and place it in the trash outside.
5
Eliminate the egg sacs. In addition to killing the spiders, you will also need to eliminate the small, cylindrical egg sacs which can contain hundreds of baby Black Widows. You will find these attached to the web made by the female Black Widow. They are usually whitish-grey in color, as they are made from the same silk as the web.
- The best bet for dealing with egg sacs is to spray them liberally with insecticide or to vacuum them up. Trying to crush or squash the egg sacs may release a flurry of tiny little baby spiders, which you will probably be unable to catch in time. If this happens, your spider infestation is likely to continue.
6
Know what to do if you are bitten. If you are not careful enough in your exterminations, or simply unfortunate, and you are bitten by a Black Widow, do not panic. The bite will probably not be painful initially, but symptoms of abdominal pain, nausea, muscle aches, dry mouth, increased body temperature, difficulty breathing, and eyelid swelling may soon develop. The appropriate first aid response to a bite from a Black Widow is as follows:
- Clean the area around the bite and immediately apply an ice pack to the area. If the bite is on the arm or leg, try to elevate it until it is level with the heart. These measures will slow down the spreading of the venom.
- Seek medical treatment immediately. Black Widow bites can be relatively harmless, but only if adequate treatment is administered. Victims usually respond to an intravenous injection calcium gluconate or calcium salts. In more severe cases, a specialized antivenom may be administered.
- If possible, try to collect the spider that bit you (alive or dead) in a small plastic bag or glass jar and bring it with you when seeking treatment. The species of the spider can then be confirmed by a spider expert, which may help medical professionals to decide on the best treatment.
- You can call a Poison Center for more information.
7
Call a professional exterminator to deal with large infestations. If you have found a large number of Black Widow spiders in your house or yard, it may be wise to call a professional exterminator who can effectively and efficiently eliminate the entire Black Widows population. This is particularly recommended if you have small children, elderly people or pets living with you, as these groups are more likely to be seriously affected by a bite.
- If the spider infestation is large, or the spiders are nesting in hard to reach places, an exterminator will have the specialized equipment necessary to deal with this. They are also licensed to used stronger chemicals and insecticides than those available for residential use.
- If you decide to go the exterminator route, try calling several pest control agencies first to ensure that they are adequately equipped to deal with Black Widow infestations. They should also be able to quote you a price based on the size of the infestation and the area of the space to be treated.

Part 3

Part 3 of 3:

Preventing Black Widow Spiders

1
Regularly and thoroughly clean your house. Black Widow spiders like to be left undisturbed, which is why they often choose dark, neglected corners to hide out in. You can make your home much more unattractive to spiders by regularly giving your house a thorough clean, making sure that you get into every nook and cranny with a broom or vacuum cleaner. Keep secluded spaces dry and free from mold, as Black Widows love moisture.
- Black Widows are often found under window ledges and around door frames. A good way to deal with this is by washing the outside of your house with a power hose. This will flush out any nasty creepy crawlies, especially from hard-to reach places like upper level windows.
2
Reduce clutter indoors and outdoors. Built-up clutter provides a safe haven for spiders, which is why people are most frequently bitten when tackling long-overdue clean-ups, such as clearing boxes in storage areas or cleaning out closets. Leave spiders as few hiding places as possible by keeping all of your belongings well organized. Indoors, make sure to get rid of any old shoes, clothes or newspapers -- anything a spider might find refuge in. Outdoors:
- Move firewood or other debris away from the foundation of the house. Spiders love making their homes in stacked up firewood, where it's dark and sheltered. However, when firewood is stacked against the house it makes it very easy for the spider to make a dash indoors, if it feels the urge. Remove this possibility by keeping firewood (or any other materials) stacked as far from your house as possible. Also, remember to wear thick gloves when carrying firewood indoors, to avoid being bitten.
- Cut back vines, shrubs and other vegetation from the side of the building.^{[2]
  X
  Expert Source
  
  Chris Parker
  Pest Control Specialist
  Expert Interview. 21 April 2021.} Spiders often make their homes in close-growing vegetation, and vines or bushes growing on or near exterior walls are ideal. Unfortunately, vines also give these spiders easy access to windows and roof spaces, so they may be facilitating the spider's entrance to your home. Cut back any ivy, or bushes near the foundation of your house, and avoid letting garden grass grow too long.
3
Make sure your doors and windows are well-sealed. Despite the fact that Black Widows are relatively large spiders, they can still manage to squeeze through very small cracks. Make your home as spider-proof as possible by filling in as many holes and closing up as many spaces as you can find.
- Before you seal up any exterior cracks, make sure to sprinkle some residual insecticide into the space. This will prevent any spiders from entering if the cracks open again in future.
- Use a caulking gun and a tube of sealant to fill in and seal any cracks you find around the perimeter of your house. Pay special attention to areas around wires and cables, faucets and electrical outlets.
- Make sure window and door screens are in good repair, and close up any holes or tears. Make sure the screens on any air vents are tightly fitted.
- Attach weather stripping to the bottoms of all doors and windows and install door sweeps to all exterior facing doors.
4
Consider changing the light bulbs at entrances. Incandescent light bulbs used in doorways attract all manner of flying insects and creepy crawlies, providing plenty of food for the Black Widow to catch in her web. You should consider changing your outdoor light bulbs from incandescent to yellow or sodium vapor varieties, as these are less attractive to insects, and therefore reduce the Black Widow's food source.
- Keep your curtains closed at night so your indoor lighting doesn't attract more insects outside.^{[3]
  X
  Expert Source
  
  Chris Parker
  Pest Control Specialist
  Expert Interview. 21 April 2021.}
- Another method of reducing the Black Widow's food supply is to place sticky traps for catching small insects and flies around your house, or use pesticides targeted at other insects. The scarcer the food, the less likely the Black Widow will be to make her home in your home.
- However, it is advisable to leave other spider species (excluding the Brown Recluse) alone. This is because other spiders compete for food, and Black Widows prefer to settle in spaces where they are the only predator.
5
Use natural spider deterrents. Some people are averse to using chemicals around their home, especially if they have pets or small children around. Luckily, there are a couple of natural methods you can use to discourage Black Widows from coming too close:
- Encourage wrens to live in your garden. Wrens are natural predators of bugs and spiders, including the Black Widow. You can encourage them to live in your garden by installing nest boxes and filling them with items such as bread crumbs, peanut butter and apple slices.
- Scatter horse chestnuts. Some people believe that scattering horse chestnuts around your home, on windowsill and in tight corners is an effective way of keeping spiders out of your home. Chemical contained in horse chestnuts, known as saponin, repels spiders and keeps them away. This has not been scientifically proven, but many people swear by it.

Community Q&A

Question

I am planning on storing my luggage in the basement in plastic bags. Would white bags be better than black bags to discourage black widow spiders?

Community Answer

Unfortunately, the color itself will not discourage black widow spiders. White bags, however, will make it easier for you to spot them.
Question

How do I safely remove black widow egg sacs?

Community Answer

Whatever you do, do not crush it. Hundreds of baby black widows will emerge and roam free, and you will have a much bigger problem on your hands. Instead, get some gloves and try applying a safe pesticide onto the egg sac. Drop it into a container or an airtight bag and throw it out once you're done.
Question

Can I get rid of them without killing?

Community Answer

You might have to kill, because the babies from prior will stay where their mom set them up.

Warnings

As stated before, black widows are highly venomous and should be treated with caution.

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Watch for Brown Widows. There are some very similar spiders in great abundance in many states right now. These are Brown Widows, and they have a very similar appearance to the Black Widow. They have the same hourglass shaped mark on their underside, but it may be orange or other shades of color, and not usually red. Their body coloring is basically brown, but can be lighter to dark shades. They can also have many colors/patterns on the top side that resemble a tattoo. While Brown Widow bites are also toxic, they deliver less venom, and so bites are only locally affected in the bite area and thus much safer than the Black Widow's. Their egg sacks are similar to the Black Widow, but have spikes protruding all around the egg sack which still resembles the basic shape of a very small cotton ball like the Black Widow. These Brown Widows are apparently much more abundant and are known for making webs in many more locations and heights than the Black Widow. Reports include webs at an adult's eye level. They are found under trash can handles, under lawn chairs, and even out in the open on chain link fencing. These require as much caution as the Black Widow. They don't attack when their egg sack is threatened, but instead will play dead. They make many more egg sacks than the Black Widow. If you find the spiky cotton ball egg sacks, you have Brown Widows. You can hunt them using the same procedures listed above.

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