In this guide, you’d find out the two significant signs of black widow spider infestation.
You’ll find out where to look for these signs of infestation. In other words, you’ll get the answer to the question of where black widow spiders hide inside your home.
You’ll also learn four easy steps to get rid of black widow spiders in your home.
Plus, we’ve also covered some important questions that our readers have on black widow spiders.
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What Does Black Widow Spider Look Like?
These spiders are black, and the females are at most 0.4 inches (10mm) in length.
Black widow spiders are spherical with distinct hourglass-like red marks on their abdomen.
The males are shorter than the females.
After mating with the male, the female eats the male spider. But experts believe that this isn’t a regular occurrence.
Baby black widow spiders are orange and white-colored. With successive moltings, baby black widow spiders turn black when they reach adulthood.
The lifespan of a black widow spider is 1-3 years. It takes one year for a black widow spider to turn into an adult from the time it hatches out from the egg.
Types Of Black Widow Spiders
In the US, there are three types of black widow spiders. They’re the southern black widow, the northern black widow, and the western black widow spiders.
All three of them have similar looks, shiny black, with the only difference, lies in the red spots on their abdomen.
The southern black widow spider has a clear red hourglass on its abdomen.
Southern black widow spiders are common in hot and humid southern states.
The northern black widow doesn’t have it, but some northern black widow spiders have it, but not like a perfect red hourglass.
In contrast, the western black widow spider has disconnected red dots or triangles on its abdomen.
Where Do Black Widow Spiders Live In The US
You’ll find black widow spiders all across the US.
Residents of Mexico and Canada also come across black widows in their homes.
2 Signs Of Black Widow Spider Infestation
Black widow spiders hide in places with low foot traffic that don’t receive much natural light.
So, areas like attics, basements, storage rooms, crawl spaces, and cellars are ideal for black widow spiders to hide.
If there’s a black widow spider in these places, you’ll see two signs of infestation –
- Black widow spider web.
- Egg sac.
Each of them is unique when it comes to their looks and size.
Let’s take a deeper look into each of the signs of infestation. That’ll help you to recognize that there’s a hiding black widow spider in your home.
First Sign Of Infestation – Black Widow Spider Web
The black widow spider web looks very haphazard and irregular.
It looks like that the spider constructed it in a hurry without much thought.
But it’s not like that. You’ll find out the construct of the black widow spider web in a minute.
Before that, let’s look at their size.
The black widow spider web looks asymmetrical, and it measures up to 14 inches in length.
The breadth of the black widow spider web is somewhat the same as the length. But it can vary depending on the width of the cramped space.
Black widow spiders don’t spin their webs in places where common house spiders do. It means that you won’t find black widow spiders’ web at higher locations like on the ceiling.
Instead, black widow spiders spin their web near the ground level.
So, in places like attic, basement, storage rooms where black widow spiders build their web, the web is a few inches above the ground.
There are reasons for it.
First, black widow spiders hunt anthropods that crawl rather than that flies. So, bugs like roaches and ants are their typical prey.
Second, black widow spiders don’t use their web only for the sake of hunting. They also use it as a defense against predators and as a place to retreat.
Being closer to the ground and building their webs in cavities and hard-to-reach places keep the black widow spider safe from predators.
Black widow spiders hang upside down in their web with their abdomen with red spots facing towards you.
Experts believe that this position is a defense mechanism to ward off predators.
The web of the black widow spider looks like a tangled mess. But it’s a thought-through structure that the spider weaves during the daytime.
The web of the black widow spider has three layers – the top layer, the middle layer, and the bottom layer.
Each layer performs a particular function, but as a whole, these layers serve two purposes – to keep the black widow spider safe and to catch the prey.
The first layer consists of the strongest of threads the black widow spider weaves.
The primary purpose of the first layer of the web is to protect the nest from any debris or waste. The secondary objective is to catch a flying bug.
These threads are so strong that you can even hear a ripping sound when you’re breaking them.
The second layer is a jumbled-up mess. It has the most number of threads.
It’s in the second layer where the black widow spider hangs upside down with its abdomen exposed to the front.
The third layer catches all the crawling bugs. The black widow spider web weaves vertical sticky traps to entrap the crawling bugs.
The black widow spider can also hide away from the nest, lurking and waiting, till there’s a trapped bug in the web.
If there’s stationary prey on the ground, then black widow spiders can slowly drop down on the target from a height of 8-10 feet to catch it.
So, if you see a jumbled-up chunk of white threads in dark and unfrequented corners of your home, then chances are a black widow spider is hiding there.
Second Sign Of Infestation – Black Widow Spider Egg Sac
The egg sacs of black widow spiders contain eggs.
The egg sac is whitish-grey, spherical, with a tiny notch at the tip. Black widow spider uses the same threads that it uses to spin its web.
With a diameter of 0.4-0.5 inches, the egg sac can contain 250-300 eggs. And a female black widow spider can spin 8-10 egg sacs with eggs in each of them.
And where do you find these egg sacs?
You’d find them in the places where they hide inside your home. In nature, you’d come across black widow spider egg sacs in holes, crevices, beneath stones, and logs of wood.
The eggs in the egg sac take two weeks to hatch. After that, the spiderlings remain inside the egg sac till they molt or shed their skin the first time.
After their first molt, baby black widows break through the sac.
Adult female black widow spiders are very aggressive near the egg sacs. They’d bite anyone to defend their egg sacs.
How To Get Rid Of Black Widow Spiders In Home?
Now that you know where black widow spiders hide and spin their webs, it’s time to get rid of them.
Let’s find out how to get rid of black widows inside your home. Then we’d get into the process of getting rid of black widows outdoors in your yard or garden.
As you know by now, black widow spiders hide in dark, cluttered, and not-often-visited places inside your home.
Attics, cellars, storage rooms, and basements are a few places inside your home where black widows hide.
Here’s what you’d need to get rid of black widows in your home –
- A vacuum cleaner
- An oil-based pesticide like Pyrethrin
- Essential oils like peppermint essential oil
- An insecticide spray like Terro Spider Spray
- Spider baits
But before that, remember that black widows can bite you to defend themselves.
So, it’d be best if you wear gloves and boots before you go into the mission of getting rid of black widows from your home.
Here’s a step-by-step guide to getting rid of black widows in your home.
Step#1 – Start Vacuuming The Cluttered Spaces
Why start with vacuuming instead of removing the clutter?
It’s because if you begin with removing the clutter, it will make the black widows run away and hide.
You don’t want that.
Vacuuming would not only clean but also suck in the black widow spider.
Use the vacuum cleaner right on the black widows’ web. It’ll get rid of the spider’s web and remove the black widow hidden in the web.
If you’ve come across an egg sac, don’t use your vacuum cleaner on it.
Let it remain idle. We’ll tackle it in the next step.
Once you’ve removed all the visible black widow spider webs, then you should move into removing the clutter in the space.
While clearing up the clutter, pay close attention to cardboard boxes and newspaper piles.
There might be black widows hiding in there.
Step#2 – Get Rid Of The Egg Sac
It would be best if you don’t use a vacuum cleaner on the egg sac or try to poke the egg sac.
If you try to poke it, you might break the egg sac. That’ll cause the baby spiders inside the sac to break away and hide.
Secondly, while vacuuming the egg sac, you might invite the wrath of the mother black widow spider.
So how to deal with it?
The best way is to deal with it to pour a generous amount of oil-based insecticide like Pyrethrin on the egg sac.
It’ll penetrate the egg sac and kill the eggs or tiny black widow spiders in the egg sac.
Wait for a few minutes after pouring Pyrethrin on the egg sac.
Let it settle down for a while on the egg sac, and then use the vacuum cleaner on the sac to get rid of it.
Step#3 – Spray Essential Oils To Repel Black Widows
Once you’re through with removing the webs, it’s time to make your space impregnable.
And the best way to do it is to spray a mixture of peppermint essential oil and water
Essential oils have insecticidal properties that repel bugs and spiders.
But essential oils don’t kill bugs and spiders.
To kill the black widow spiders, which we don’t recommend, you can use dust-based or liquid spray insecticides.
Use dust-based insecticides in places which you or your pets don’t frequent at all.
If you’re using liquid spray insecticides, ensure that you spray them right on the black widow spider to kill it.
Terro spider killer spray is the best for this purpose.
Also, spray the insecticide in all the corners of the space. That’ll stop other bugs and spiders from invading the area.
Alternatively, you can also use white vinegar instead of essential oils.
White vinegar leaves a nasty pungent smell.
So, once the black widows are gone, don’t forget to clean your space to get rid of the vinegar smell.
Step#4 – Keep Spider Baits To Lure Black Widows Out Of Hiding
Black widows can hide anywhere while you’re getting rid of them.
So, after going through the previous, you might have a black widow hiding somewhere in your home.
And the best way to ensure that your home is free of black widows is by keeping spider bait traps.
Keep the spider baits near tight places where black widows can hide.
Keep the spider baits after sunset because black widows are nocturnal, and they’re most active during the night.
If there’s any hiding black widow in your home, you’ll find it sticking with the spider baits the following day.
Dispose of the spider bait along with the spider outside your property.
Spiders and bugs sneak inside your home from outdoors through tiny gaps and cracks on your home’s walls, windows, and doors.
Use a silicone-based sealant to caulk those gaps.
Silicone-based sealants are strong and lasts for at least two decades.
The best part is that bugs and spiders cannot chew through silicone based caulks.
How To Get Rid Of Black Widows In Garden And Yard?
Not doing your due diligence to get rid of black widow spiders in your yard won’t make your home free from black widows.
They sneak inside your home from outdoors.
And the chances are that if you’ve found black widows inside your home, there are quite a few in your yard or garden.
The signs of infestation of black widow spiders in your yard are as same as the signs inside your home.
You’d need to look for the signs in places like firewood piles, mulch, shrubs, bushes underneath the patio, and the holes and cracks on the walls.
They’d sneak inside your home looking for a mate, food, and shelter.
So, how do you ensure there are no black widow spiders outdoors?
It’s simple, make your yard uninhabitable for them.
It means that you’d need to get rid of all the wastes and organic debris in your yard or garden.
Use the same essential oil spray or vinegar spray that you’ve used inside your home on firewood and mulch.
That’ll repel any bugs and black widows hiding there.
You can also use plant-friendly insecticide sprays in your yard or garden to kill the black widows.
Trim any overgrown shrubs and bushes. Black widow spiders spin their webs in them.
If you see egg sacs, don’t break it or step on it. Pour an oil-based insecticide like Pyrethrin and leave it for a few minutes.
Then use a scoop to pick the egg sac and dispose it outside of your property.
Use outdoor lighting sparingly. It’s because light attracts bugs, which in turn, will attract the black widow spiders.
Instead of regular outdoor lights, you can use sodium vapor bulbs outdoors.
Sodium vapor bulbs don’t attract bugs.
Spiders kill and eat all the bugs and pests in your yard. That’s one of the positive sides of spiders.
That’s why it isn’t always advisable to kill spiders. Instead, it’s better to repel them rather than kill them.
Are Black Widow Spiders Poisonous?
Black widow spiders are poisonous. Black widow spider’s poison is 15 times stronger than rattle snakes’ poison.
But would you die if a black widow spider bites you?
No, you won’t. Black widow spiders’ bite rarely kills humans.
If a black widow spider bites you, you’ll feel severe pain, swelling, and a burning sensation on the bitten area.
The bitten area will turn red, and it might have two fang marks on it.
If you’re severely allergic to bug bites, then you’d feel severe cramps, abdominal pain, nausea, dizziness, and vomiting.
See a doctor asap if a black widow spider bites you.
If You Find A Black Widow Spider In Your Home, Are There More?
If you find a black widow spider in your home, chances are there can be more.
If your home is inhabitable for one black widow spider, then for sure, it’s livable for more of them.
Spiders also sneak into your house in search for prey, shelter, and, of course, to mate with other spiders hiding inside your home.
In a large yard, basement, and garage, there can be multiple black widow spiders, especially when it’s dirty, cluttered and don’t receive much of light.
That’s why it’s always advisable to clean the entire area where you’ve found the signs of black widow spider infestation.
Do Black Widow Spiders Live In Groups?
No, they don’t. Black widow spiders are solitary arachnids.
Male and female black widow spiders come in contact with each other only during the mating season, which is spring.
Do Black Widow Spiders Jump?
No, black widow spiders don’t jump.
They’ve got very tender legs that don’t have enough strength to make the black widow jump.
But black widow spiders are expert climbers and hangers.
Black widow spiders can quickly descent by using their silken thread onto any stationary prey on the ground.
Do Hairspray Kill Black Widow Spiders?
Yes, hairsprays are an effective alternative to insecticide sprays to kill black widows and all types of spiders.
But you’d need to spray the hairspray straight onto the spider to kill it.
There are two signs of black widow spider infestation –
- Black widow spider web near the ground or in the cavities.
- Black widow spider egg sac.
In this guide, you’ve found where to look for the signs of infestation. And, most importantly, you’ve also found out how to get rid of black widows in your home and yard.
Spiders are sneaky creatures and great at hiding during the day.
To find out how to bring out a hiding spider, read our post on luring a spider out of hiding.
We’re Mark and Jim. We were serial pest killers for almost all of our lives. Through this blog we spread pest murdering tips to people like you who want to keep their homes pest free.