Detecting black widow spider infestation is hard. These spiders don’t wander around in the house openly like other pests.
They live in the secluded areas of the house, making it difficult to spot them.
But with a slight bit of investigation and curiosity, you can detect the signs of black widow spider infestation that confirm their presence.
This guide is now going to reveal the five signs and the areas where you’re most like to find them.
Sightings Of Adult Black Widow Spiders
The first sign of black widow spider infestation is the sighting of adult black widow spiders.
These spiders aren’t easy to spot in the house because of their reclusiveness, but once you do, they’re quite straightforward to identify.
Their shiny black globular bodies with an hour glass figure in the abdomen is an make them easily recognizable.
Finding one black widow doesn’t mean that there’s only black widow spider in your home. In fact, it shows that there can be more of them in the house.
Female black widows produce smooth, round, silk egg sacs that are about 1 cm in diameter. They usually hide the egg sacs in their web and each egg sac can contain hundreds of eggs.
If you find one or even multiple egg sacs in your home, it’s a strong sign of black widow spider infestation.
Black Widow Webbings
Black widows build their haphazard-looking irregular webs near the ground. Unlike other house spiders, they don’t build their webs between the window frames or at the corner of the ceilings or walls.
These webs are at the corners of the floor or in the wall cracks.
The webs don’t don’t have a funnel like structure that is a common feature of other spider webs near the ground.
Black Widow Bites
Black widow spider bites are rare. It’s because like most spiders are shy and they avoid human contact at all costs.
Also, black widows don’t actively seek humans to bite because they’re not parasites.
Bites occur when they feel threatened or cornered, or when they accidentally get pressed against your skin like when you step on them barefoot.
The bite wound doesn’t look distinctive but there are certain features that indicate that the bite is from the a black widow.
The bite site display two puncture wounds side-by-side about 1 mm apart. This is the place where the spider entered it’s fangs.
Some people might feel a minor prick during the bite, while others may feel nothing at all. However, within a few minutes to an hour, excruciating pain develops at the bite wound.
Swelling and redness appears on the bite area. In some cases, a target-shaped lesion may appear, which is a red central area surrounded by a pale ring and an outer red ring.
Muscle pain and cramping, especially in the abdomen and back, as well as sweating, chills, tremors, nausea, and a rash or itching follow.
Some people can also show symptoms like headaches, difficulty breathing, dizziness, fever, chest pain, headache, or a significant increase in blood pressure.
If left untreated, the bite wound becomes large and spreads like skin ulcer. But this is not skin necrosis that occurs during the brown recluse bites.
This is the body’s immune response in the skin against the black widow’s venom.
You must seek immediate medical attention if a black widow bites you.
Finding Dead Insects
The presence of insects in the house attracts spiders including the black widow spiders because spiders are carnivores and they hunt other insects.
Spiders sneak inside the house when their prey exist in your home.
If you start noticing more dead insects in certain areas of your home, it might be a sign that a predator, like a black widow, is nearby.
What Do Female Black Widow Spiders Look Like?
It’s the female black widow spiders that you should worry about. These are the ones that are venomous and they can bite.
Female black widows are shiny black with a distinctive reddish-orange or red hourglass shape on the underside of their abdomen.
Females are larger than male black widows. They grown up to 1.5 inches (38 mm) in size with their legs fully extended. Male black widows are half this size or even smaller.
Black widows have two main body parts: the cephalothorax (a combined head and midsection) and an abdomen. They have eight legs and no antennae.
The male black widows and juveniles are of similar shape but they’re not black. Males are matt gray or light brown with some light-colored markings.
Juvenile or baby black widows can be orange or white. They get darker as they grow.
Both males and juveniles are harmless and they’re not infamous for painful bites like the females.
Where To Look For Black Widow Signs?
You can’t go around randomly checking all the corners of the homes for the signs of black widows.
That would be a waste of time and energy.
Knowing where the black widows hide and where they leave behind the signs of infestation will cut short your effort to get rid of them.
Basements And Crawl Spaces
Black widows hide in the dark, secluded, and undisturbed areas of the home. That makes basements and crawl spaces ideal places for them to hide.
You’ll need to look for their signs in the corners, crevices, and in the boxes that you store there.
The presence of basement bugs and insects like earwigs and roaches that hide in the crawl spaces make these places a perfect hiding spot for black widows.
Garages And Sheds
Cluttered garages and sheds are safe havens for black widows. They can easily slide into the clutter and stay protected from any predators and most importantly from your line of sight.
The places under workbenches, behind tool boxes, cardboard boxes, and other place that provides cover are ideal hiding spots for them.
Closets And Storage Areas
Stuffed closets, wardrobes, and storage areas are cozy environment for black widow spiders. They’ll sneak inside them and quietly hide in the layers of clothing and other materials that you keep.
These spiders can also get inside shoes that you’ve kept and didn’t wear often.
Before black widows move inside the house, they hide in the woodpiles, piles of debris such as leaf litter, mulch beds, underneath rocks and plant pots, and in seldom-used grills or outdoor equipment.
Like basements, attics also provide the dark secluded corners and quiet environment that black widows prefer.
The dark corners in the attic, the voids on the attic walls, and the areas behind or under stored items in the attic are all prime areas for these spiders to hide.
Many insects and flies hide in the attic, making it a perfect hunting and breeding ground of black widows right inside your house.
Neglected Old Furniture
The tight areas behind or underneath old and unused furniture lying outdoors in your yard or in your basement are also hiding places for these spiders.
You move these furniture into your living space and you introduce black widow spiders inside the active areas of your home.
How Does Black Widow Infestation Start?
Like most spiders, black widows too enter homes looking for food, shelter, and safety.
The presence of other insects, or a thriving pest infestation such as roach infestation, draw the spiders inside.
Inclement weathers outdoors also push these spiders indoors while they’re looking out for alternative places to hide.
Easy access points, such as cracks on the windows, home’s walls, and doors allow the black widows to crawl through them and hide in the secluded areas of the house.
Mating calls from female widows inside the house is also responsible for drawing a ton of male black widows to the house.
These calls aren’t actually some kind of sound. Females release pheromones that emit a scent which the males can pick up.
Do Black Widows Live Together?
No, they don’t. Black widows are solitary arachnids that don’t live in groups.
Black widows only come together during the time of mating.
You’re most probably going to find one black widow in a confined area but that doesn’t means that there’s only one. That’s a clear sign that there are more in the house.
On top of that, black widows are nocturnal spiders. They’ll make any move in the house when it’s dark. So, finding them makes it even more challenging.
Hire Professional Pest Control To Get Rid Of Black Widows
Don’t rely on DIY methods to get rid of black widow spiders. You’ll expose yourself to the risk of black widow bites.
Black widows will bite you if get too close to them or if you try to mess up with their egg sacs.
These spiders can be difficult to spot, especially when you’ve a big house with a lot of clutter. So, I don’t recommend that you deal with black widows personally.
Always hire a professional pest controller to do the job.
Can Black Widow Spiders Harm Pets?
Yes, your pets are at a bigger risk of black widow bites than you are. Dogs and cats are more susceptible to their bites than humans are and can experience severe symptoms.
Your pets can show symptoms like pain, muscle rigidity, abnormal behavior, salivation, vomiting and paralysis. Pets can also die from a black widow bite.
So, it’s please take your pet to a veterinarian asap if you’re noticing these symptoms.
Black widow spiders infestation signs are difficult to spot and are only visible in the places where they hide.
The five signs of black widows in the house are –
- Sighting of black widows
- Egg sacs
- Black widow webs near the ground
- Black widow bites
- Finding dead insects
Finding any of these signs should alert you about a possible infestation. And because of the risks involved, you must hire a pest controller to get rid of them.
Nang Chen is an Entomologist and Arachnologist who is associated with Vienna’s museum of natural history. He’s also a consultant with real estate groups, insecticide conglomerates and law enforcement groups as a forensic entomologist. Nang Chen holds an M.S. from South China University and he’s a regular contributor to our site.