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Black Widow Spiders | Facts, Behavior, Identification & Control

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Black widow spiders belong to a genus of spiders commonly referred to as true widows and did you know that despite being called widows, there are both male and female black widow spiders?

Bet you did not know that!

  • What is a black widow spider?
  • What do black widow spiders eat?
  • Are black widow spiders venomous?
  • Where do black widow spiders live? etc

These and many more questions are what we @pestclue have contained in this article, with answers accompanying these questions.

 

Did You Know Facts About the Black Widow Spiders?

To help you better separate fact from fiction, here are eight amazing details about black widow spiders:

  • Why Marvel Character is Called “Black Widow”

In the year 2019, it was discovered that one of the beginners of the fictional superhero group (the Avengers), the black widow, was given the name due to her ability to escape tough situations without being noticed.

 

  • They are far from the world’s deadliest spiders

Because of the name that this spider bears, many people believe them to be the world’s deadliest spiders and the most venomous of all the spider species.

Well, in North America, the Black widow spider is the most venomous as its venom is 14 times toxic than that of a rattlesnake since it contains Alpha-latrotoxin (a chemical that stimulates nerve cells) responsible for immense pain.

Despite being the most venomous spider in the whole of North America, that does not place them close to the most venomous spiders in the world. In fact, their close relative, the Australian redback spider, is more venomous than the black widow spiders.

 

  • An antivenom exists for bite victims

In the year 1930, antitoxins were created to counter bites from the black widow spiders. Below is a breakdown of how these antivenoms are made:

  1. Pharmaceutical producers expose horses to a minimized amount of widow spider’s venom.
  2. The horse’s immune system reacts by creating antibodies that target chemicals in the venom.
  3. Pharmaceutical producers draw blood with those antibodies and purify them to be used in victims.
  4. The antibodies neutralize venom by flagging a person’s immune system to destroy the pain-inducing chemicals.

 

  • Not one, but many species exist

These spiders comprise not just one but many species.

In North America alone there are close to 3 species; the Latrodectus variolus (Northern species), the Latrodectus mactans (Southern species), the Latrodectus hersperus (Western species), etc. and these 3 species go by the common name black widow.

IN NORTH AMERICA
BLACK WIDOW SPECIES WHERE TO FIND THEM
Northern Species ·      United States

·      Southern Canada

Western Species ·      Along the west coast

·      In the desert

Eastern Species ·      Southern United States

In the year 2019, the Phinda button spider was discovered in South Africa and added to the taxonomic genus of the black widows.

 

  • The young spiders are cannibals

Just like the Marvel character “Black Widow” who was trained from a young age to kill, the young widow spiders have shown the killer instincts more aggressively.

The young’s are more aggressive than the adults and possess a higher rate of cannibalism than the adults. Based on research carried out in the year 2016, the spiderlings hatch together but at different times; the large ones among them will immediately feed on the smaller ones (cannibalism)

 

  • Females sometimes eat their male counterparts after copulation

Why were they called black widow spiders in the first place? well, it’s because scientists observed the cannibalistic behaviors of the females towards the males after mating.

This disaster is usually rare though and will only occur if the male has no route of escape. Cannibalistic behaviors of the females are very rare in other related species such as the Redback spiders, Brown Widow Spiders, etc. since the males use a technique known as traumatic insemination.

Below is how traumatic insemination works:

  • The unlucky male meets an aggressively hungry female.
  • He (the spider) wants to mate with her and also wishes to survive doing it.
  • The male uses its fangs to pierce a hole in the shell of the female.
  • Mating occurs.

The male is able to pass on its genes without getting eaten by the female.

 

  • The vibration of their webs tingle their senses

 

  • The red spot on their backs grant them protection from predators up high and lurking below

 

  • Their range is expanding; Climate change is one of the responsible factors

It has been observed that climate change is one of the factors affecting the population of these spiders.

During winter periods, they go into a state known as “overwintering” where they find a protected area and stay dormant till the temperature is okay for them to come out and mate.

Research has shown though that thes spiders are beginning to go further into regions where they were rarely seen; The Northern black widows have now moved 31 miles further into Canada than they did in the year 1960.

 

  •  Black Widows Are Not House Spiders

Due to their habit of building irregular webs, many people believe them to be home dwellers but in fact that is a misconception.

Black widow spiders are rarely found in human habitats, and will somewhat be beneficial to humans if they are found in your habitat {they can help in reducing pest (harvester ants, fire ants, etc) population in the home}.

Black widow spiders will rather live in:

  1. Hollow tree stumps
  2. Outdoor vegetations
  3. Rock piles
  4. Piles of wood
  5. Burrows that have been abandoned by rodents

 

What is the Behavior of Black Widow Spiders?

Just like other spider species, the widow spiders have poor eyesight and rely solely on vibrations reaching them through their webs (these vibrations come to them to warn them of a larger threat, or signify them of the presence of a prey).

Unlike most venomous spider species, the widow spiders do not bite unless they are threatened, trapped, and have no route of escape. Rather than bite, these spiders usually preferre to:

  • Play dead
  • Shoot silk at the threat

Want to know more behaviors of the black widow spiders? then read on and give your mind that satisfaction it requires.

 

What do Black Widow Spiders Eat?

Before knowing what these spiders eat, you should know how they eat:

  • Black widow spiders process (in human terms; cook) their food (prey) outside of their bodies.
  • The vibration of the web signifies the presence of a prey.
  • The prey is injected with digestive enzymes.
  • The digestive enzymes softens and liquefies the prey.
  • The spider consumes the unlucky prey.

As the stomach of the spider fills up, the abdomen expands.

Just like most spider species, the widow spider is capable of surviving for months without food. Infact most species survive for up to a year without food.

Below is a breakdown of what the black widow spiders will feed on:

 

Where can You find Black Widow Spiders?

As mentioned earlier, these spiders are very rare Inside the home and typically hide in dark locations such as

  • Garages
  • Dark corners
  • Basements
  • Behind furniture
  • Under desks
  • Closets, etc.

Their nest sites are usually near burrows that have been abandoned by rodents,  around construction openings, or wood piles. Low shrubs also are common sites for black widow spiders to occur.

Black widow spiders are rarely found in human habitats, and will somewhat be beneficial to humans if they are found in your habitat {they can help in reducing pest (harvester ants, fire ants, etc) population in the home}.

Black widow spiders will rather live in:

  1. Hollow tree stumps
  2. Outdoor vegetations
  3. Rock piles
  4. Piles of wood
  5. Burrows that have been abandoned by rodents

 

How Does a Black Widow Spider Reproduce?

When a male widow spider is mature, it:

  • Spins a sperm web
  • Deposits semen on it and charges his palpi with the sperm.

After mating, the female deposits her eggs in a silk container where they remain camouflaged and guarded. A single female can produce 4 to 9 egg sacs in one summer, each containing about 100 – 400 eggs.

Despite being much in population (spiderlings), only about 40 will survive due to the following factors:

  • Lack of food
  • Lack of proper shelter
  • Cannibalistic behavior by the larger spiderlings towards their smaller siblings.

The females can live for up to 5 years, while the lifespan of the male is somewhat shorter.

Additional Behaviors of the Black Widow Spiders:

  • They are Shy: Black widows are shy in nature, and socialize only during copulation.
  • They have Nocturnal Behaviors: Black widows are nocturnal and spin webs during daytime.
  • They Hang upside down: They can sometimes be seen hanging upside down from their webs, exposing their hourglass abdominal markings.

 

How do I Identify A Black Widow Spider?

Black Widow Spiders
Picture of a Black Widow Spider

Female black widows are called these (black widows) because of their cannibalistic behaviors towards the males, especially during mating.

The black widow spiders have an hourglass shaped marking below their abdomens which usually ranges from red, white, yellow, orange, etc in color. They also have a small, red-colored dot near their silk-spinning organ (spinneret), which is been separated from the hourglass.

Female Male
A large female black widow spider can grow to about 1.5 inches (38 millimetres), including leg span. Male black widow spiders are half the size of the female or even smaller.
They have hourglass markings at the underside of their abdomens. They are also usually dark brown with varying colours of stripes or dots, with no hourglass mark.

 

How Do I Control A Black Widow Spider Infestation?

It has been certified that these spiders rarely invade human habitats, but what if your home is one of those rare cases? below are detailed insights about the widow spider’s infestation.

How Did I Get Black Widow Spiders In My House?

Tall grass and piles of firewood or debris are breeding grounds for these spiders, and will attract them to come and search for food, hiding spots, shelter, and build webs.

If you’ve already got an insect infestation in your home, then these pests (black widow spiders) are obviously coming to pay you a visit, as they feed on ants, mosquitoes, roaches, flies, etc. Leaving cracks and crevices in your windows or doors is a sure invitation letter to these pests.

Although these pests are somewhat beneficial to man, they (especially females) will attack humans when they are provoked. Studies show that the black widow spider delivers the most toxic spider bite in the United States, as its venom is comprised of neurotoxins that affect the nervous system.

 

What are the Signs of a Black Widow Spider Infestation?

Now that you can boldly identify these spiders if you ever see one. Below are signs of a possible infestation by these guys:

  • Messy, irregular webs (usually located near ground level and under a protected ledge such as under lawn furniture or wood piles)
  • Visible sighting of the females with their notable red hourglass markings.

 

How do I Get Rid Of A Black Widow Spider Infestation?

  • Make use of strong scents
  • Make use of Vinegar
  •  Use a Vacuum
  • Insecticides and pesticides is one sure way of getting rid of this pest, alongside others
  • Make use of Insect traps
  • Make sure to remove web-building spots
  • Ensure to limit outdoor lighting
  • Use birds and plants as deterrents (this discourages them from visiting)

 

Conclusion

The black widow spiders are not a serious threat to humans unless they are threatened, trapped, or confined, etc. so theres obviously no reason to want to get rid of them. Just saying though!

Feel free to drop your comments (positive/negative) (inquiries/queries) as we will be anticipating your respnse to this article.

Ememobong Umoh is one of the prominent authors of Pestclue. He is an undergraduate who is experienced in the field and has written numerous mind thrilling articles about pests and animals.

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