3 Signs Of Black Widow Spider Infestation You Must Never Ignore

Black widow spiders are one of the most venomous spiders inside your house.

Black widows deliver a toxic bite that can lead to intense discomfort and pain; you’ll need medical attention after the bite.

In this guide, you’ll find signs of black widow spider infestation and where you notice them.

You’ll also learn to identify the black widow spiders and the best method to get rid of them inside the house.

Black Widow Spider Infestation Signs

The telltale signs of black widow spider infestation in your home are –

  1. Haphazard messy black widow spider webs near the grounds in the secluded areas of your home
  2. Sightings of adult black widow spiders
  3. Egg sacs

Let’s get into each of these signs to learn more about them.

Black Widow Spiders Web

How to get rid of black widow spiders in home

Black widow spiders spin webs a few inches above the ground level in cluttered areas like your home’s attic, basement, and storeroom. The black widow spider builds their nests in these areas because they hunt crawling insects more than flies and mosquitoes.

Bugs like kissing bugs, beetles, roaches, and other pests hide in places where there are fewer human footfalls.

The female black widows will rest in the nest upside down, with their red hourglass shape on the underside exposed.

The male black widow spiders look different. They don’t have the red hourglass marking on their abdomen like the female black widows.

Instead, the male black widows have many red spots on their abdomens. The males can also have white stripes on the abdomen.

The males are smaller than female black widow spiders. The adult male grows only half the size of the female black widow.

Also, the males are not jet-black like females. The male black widows are dark brown or gray.

The black widow spider’s webs may look like messy, irregular webs. But the black widow spiders structure them very well to catch their prey.

It’s divided into three layers. 

The first layer, the strongest layer, protects the web from collapsing because of any debris or waste falling onto it.

The webbing is robust. You’ll hear a snatching sound when you break the first layer.

However, it’s not the second layer that traps the prey, despite having the densest webbings. It’s because the black widow spider uses it as a retreat and to wait for prey patiently.

The black widow spider hangs upside down on the second layer exposing the red hourglass shape on its abdomen. 

It’s a defense mechanism. 

Predators in nature avoid bright colors because it’s a sign of venom. 

Exposing the shiny red hourglass marking by exposing the underside gives the same hint to the predators and keeps them away. 

The third layer is the stickiest portion of the web. That’s the layer for trapping the insects. 

When the insects get stuck on the third layer, the black widow spider picks it up by picking up the vibrations on the web. 

The black widow goes to the third layer, inserts its fangs, injects the venom, and paralyzes the prey before eating it

Sightings Of Black Widow Spiders In The House

Black widow spider hiding

There’s no convincing sign of black widow spider infestation in the house than the sightings of adult black widow spiders.

Like most spiders, the black widows are also shy. And they avoid human contact.

So, they hide in cluttered places and dimly lit locations where minimal human footfall exists.

The most common hiding places for a black widow spider in your house are the attic, crawl spaces, and underneath furniture in the basement.

Black widows also hide inside cardboard boxes stuffed with old newspapers, books, and magazines in the storeroom and basement.

Sightings of black widow spiders inside the home indicate that your home has a black widow problem.

Outdoors, black widow spiders hide underneath rocks, in firewood piles, and tall grasses.

So, they also look for the same protected areas inside the home.

Black widow spiders have shiny black bodies. And their abdomen is the most noticeable portion of their bodies.

Black widow spiders have eight legs. Black widows also have a comb foot line with a row of curved bristles on their hind legs that helps them to cover the trapped prey by spinning a silk webbing on them.

The female black widow spiders’ hourglass shape isn’t visible when crawling. The characteristic red hourglass on the underside is visible when hanging upside down in their irregular webs.

But there’s a catch.

You won’t see the black widow spiders inside the home as easily as other spiders like house spiders.

Many people come across black widow spiders while cleaning the cluttered places inside their homes.

And these spiders have a habit of even sneaking inside places like closets and the storage section underneath beds.

Black Widow Spider Egg Sacs From The Female Black Widows

Black widow spider egg sac

The female black widow spiders will also lay eggs in your house. After laying eggs, the females will combine the eggs in the egg sacs.

The egg sacs are silken balls that females weave. The female black widow spider can lay hundreds of eggs and combine them in multiple egg sacs.

Each egg sac can contain 400 eggs.

The females keep the egg sacs in the wall voids, cracks, and gaps in their hiding places.

They also stick the egg sac with their saliva behind or underneath furniture and inside cardboard boxes.

Sightings of these egg sacs are a clear sign that there’s a black widow spider infestation in your home.

The females don’t go far away from the nest where they keep the sac. And they’re fiercely protective of their egg sacs.

The black widow spider can come out of nowhere and bite anyone tampering with the egg sac.

Black Widow Spider Bites

A bite from a black widow spider is the most toxic spider bite that you can ever get.

The brown recluses and the black widows can deliver a bite in self-defense when they feel threatened or when you try to handle them.

Black widow spider bite has serious symptoms. Symptoms include difficulty breathing, itching, redness and pain in the bitten area, nausea, chills, sweating, and increased blood pressure.

Black widow spiders inject venom when they bite. It can also affect the nervous system, which leads to other symptoms like chest and abdominal pain.

That’s why you must seek immediate medical attention within the first hour of the bite.

Black widow spider bites when you engage in black widow spider removal on your own with a vacuum cleaner and without wearing protective gear.

You can use a vacuum cleaner to remove the messy webs of the black widow spiders above the ground level.

But the black widow can bite if it thinks the egg sac is at risk from you or when they get pressed against your skin.

Bites can also result if you try to handle the black widows.

However, the black male widow doesn’t bite. It’s only the females that can attack humans.

I Found A Black Widow In My House, Are There More?

Yes, the presence of one black widow spider indicates the presence of more of them inside the home.

During the mating season, many males will enter homes to mate with females hiding inside the home.

The females will lay eggs inside the house. If you don’t remove these eggs, they lead to infestation inside the house.

Many tiny baby spiders, which are spiderlings of the black widows, hatch out of the egg sacs and disperse and hide in different areas of the house.

Professional Pest Control Is The Best Way To Get Rid Of Black Widows

Black widows can be a serious pest problem in your home, and their presence will expose you to the risk of bites.

Plus, finding and removing the egg sacs is vital for eliminating black widow spider infestation in the house.

If you decide to do it yourself, you’ll expose yourself to the risk of the black widow spider bite.

That’s why, if you notice the signs of black widow spider infestation in the house, then it’ll be best to hire a professional and reliable pest control company to do the job.


Physical sightings of black widows, messy webs just above the ground level, and silken spherical egg sacs are the three signs of black widow spider infestation.

These signs appear in the cluttered and unfrequented areas of the home that are not well-lit.

Black widow bites are nasty and can cause serious complications that can put you at risk.

Contact a pest controller asap if you notice the signs of a black widow infestation in the house.