Black Widow Spider Male vs Female: Unraveling the Differences

Black widow spiders are fascinating creatures known for their distinct appearance and venomous bite. They belong to the genus Latrodectus and can be found in various parts of the world.

One interesting aspect of black widow spiders is the significant difference between males and females, which plays a vital role in their society, size, and behavior.

The female black widow spiders are larger and more dominant than their male counterparts. In fact, their size can be up to double that of the males.

Black Widow Spider Male vs Female
Immature Black Widow

Females are also known for their trademark black body with a red hourglass-shaped marking on their abdomens. Males, on the other hand, are more of a brownish color and lack the distinct red marking.

Mating behaviors among black widow spiders are particularly unique. Female black widows are generally aggressive and may even consume the males after mating.

This act is believed to provide essential nutrients for the female and her future offspring.

In contrast, male black widows try to minimize their risk during mating by selecting less aggressive females, performing intricate courtship rituals, and even producing a chemical signal to reduce the female’s aggression.

As evident, the differences between male and female black widow spiders are vast, transcending from their physical appearance to their behaviors.

These characteristics contribute to their successful survival strategies and have made them a subject of fascination for many.

Black Widow Spider Male vs Female: Identification

Hourglass and Red Spots

Black widow spiders, both male and female, are known for their distinct markings. Female southern black widows have a shiny, jet-black body with an orange to red hourglass marking on their abdomen’s underside.

The males, however, display spots and stripes of red, orange, and/or yellow on the upper surface of their abdomens.

Here’s a comparison of the markings:

Feature Male Black Widow Female Black Widow
Hourglass No Yes, underside
Red Spots Yes, on top of abdomen Variable, on top of abdomen

Body Size and Coloration

The body size also differs between males and females. Female black widows’ bodies are typically 8-13mm in length, measuring 25-35mm with extended legs. Male black widow spiders are much smaller with a white underbody.

A summary of body size and color for both genders:

  • Male Black Widow:
    • Smaller body
    • Black body, white underbody
    • Red, orange and/or yellow markings on abdomen
  • Female Black Widow:
    • Larger body
    • Shiny black body
    • Red hourglass on abdomen underside
    • Variable red spots on top of abdomen

It’s important to differentiate between male and female black widow spiders, as females pose a more significant threat to humans due to their venomous bite.

Immature, female Northern Black Widow

Behavior and Habitat

Web Construction and Communication

Black widow spiders create irregular, messy webs with strong silk.

These webs serve as a way to capture prey and communicate through vibrations. Here are some key features of black widow webs:

  • Made of very strong and sticky silk
  • Usually found in dark, secluded areas like woodpiles and garages

Comparing male and female black widow spiders, males tend to build smaller webs and wander more frequently in search of females for mating.

Prey and Diet

Black widow spiders primarily feed on insects such as flies, mosquitoes, and grasshoppers. The diet of both female and male black widows generally includes:

  • Insects
  • Small arachnids
  • Occasional small vertebrates

Female black widow spiders are known to be more aggressive than males when it comes to hunting and capturing prey.

Mating and Reproduction

Mating and reproduction in black widow spiders involve unique and complex behavior. Male black widows identify potential mates through pheromones on the female’s silk.

They then perform a courtship dance to avoid being mistaken as prey. The following points summarize mating and reproduction in black widow spiders:

  • Female black widows are known for sexual cannibalism, sometimes consuming the male after mating.
  • Females can store sperm for several months, producing multiple egg sacs from a single mating.
  • Lifespan: Males typically live around 6-8 weeks, while females can live up to 3 years.
Aspects Male Black Widow Spider Female Black Widow Spider
Lifespan 6-8 weeks Up to 3 years
Aggressiveness Less aggressive More aggressive
Web Size Smaller Larger

Venom and Medical Concerns

Venom Composition and Effects

Black widow spiders, specifically the female ones, are known for their venomous bites.

The venom of the black widow, a neurotoxin called alpha-latrotoxin, is reportedly 15 times more toxic than the venom of a prairie rattlesnake. The effects of black widow bites include:

  • Muscle pain
  • Diaphoresis (sweating)
  • Tachycardia (rapid heart rate)
  • Flushing (redness of the skin)
  • Hypertension (high blood pressure)
Black Widow

Treatment and Antivenom

In case of a black widow bite, it is essential to seek medical treatment immediately. Treatment generally consists of:

  • Opioid analgesics for pain relief
  • Muscle relaxants to ease muscle cramps
  • Antivenom for severe cases

Contacting local poison control centers can provide additional guidance on managing the symptoms of a black widow bite.

Black Widow

Prevention and Safety Measures

To minimize the risk of black widow encounters, follow these safety measures:

  • Avoid disturbing areas where black widows commonly reproduce, such as late spring or early summer
  • Be cautious when handling firewood, debris, or items in storage areas
  • Wear gloves and protective clothing while working outdoors or in areas where spiders may inhabit
  • Regularly inspect and seal any cracks or openings in building structures

It is important to correctly identify black widow spiders. Some key identifying features include:

  • Female southern black widow spiders are shiny and jet black with an orange to red hourglass marking on their undersides
  • Males are smaller, black, and have white markings under their bodies
  • Black widows typically range from 8 to 13 millimeters in body length, extending to 25 to 35 millimeters with their legs

Though black widow spiders are venomous, by taking proper precautions and being vigilant, the risks associated with these spiders can be reduced significantly.

Comparison of Male and Female Black Widow Spiders

Physical Differences

  • Male black widow spiders:
    • Smaller in size, around 1/4 of females
    • Brown or gray color
    • Red and white stripes on abdomen
  • Female black widow spiders:
    • Larger in size, up to 1.5 inches body length
    • Black with a signature red hourglass marking on abdomen

Both male and female black widow spiders belong to the spider species Latrodectus, which are part of the arachnid family.

Behavioral Differences

  • Male black widow spiders:
    • More mobile and active
    • Tend to wander in search of females
    • Less venomous and not a threat to humans
  • Female black widow spiders:
    • More solitary and sedentary
    • Build webs in dark corners, crevices, basements, closets, and cluttered areas
    • Prey on flies, grasshoppers, beetles, and other insects
    • More venomous and considered dangerous to humans

Black widow spiders can be found in various locations, including Florida and Texas.

Immature Black Widow

Reproduction and Cannibalism

During copulation, the male black widow spider approaches the female while she is upside down on her web.

After mating, the female may exhibit cannibalistic behavior by consuming the male. However, this behavior is not always observed in the wild.

Male Black Widow Spider Female Black Widow Spider
Physical
Size Smaller Larger
Color Brown or gray Black
Markings Red and white stripes Red hourglass
Behavioral
Mobility More active More sedentary
Threat to humans Less venomous Highly venomous
Habitat preference Wandering Solitary in dark corners
Reproduction Seek mates Can cannibalize mates

In summary, male and female black widow spiders exhibit significant differences in physical appearance, behavior, and reproductive habits.

Conclusion

Black widow spiders are captivating creatures with distinct appearances and behaviors.

The stark differences between males and females, from size to coloration, play a pivotal role in their mating rituals and survival strategies.

While the venomous bite of the female black widow demands caution, understanding their habits and habitats can significantly reduce encounters.

By recognizing their unique characteristics and taking preventive measures, we can coexist with these remarkable arachnids while ensuring our safety.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about black widows. Scroll down to have a look at some of them.

Letter 1 – Male Black Widow


Dear Bug Man,
We found this on the front door of our home in Byron, Georgia. Is it a Black Widow and is it poisonous? Thank you,
Denise West

Hi Denise
Despite originating in Georgia, this looks like a Male Northern Widow, Latrodectus variolus. There is a wonderful image that matches yours on BugGuide. From what we understand, only the female Black Widow has a dangerous bite.

Letter 2 – Male Black Widow

Male Northern Black Widow?
Location: Greensboro, NC
April 10, 2012 12:40 pm
We found this guy in the windowsill at our house in Greensboro, NC. After a few hours googling and much deliberation we decided it must be a Male Northern Black Widow, any chance you can confirm it for us?
We could never get a very good picture of it’s underbelly but could tell there was a red mark, just not sure the shape.
Thanks for the help!
Signature: Not 100% sure

Male Widow Spider

Dear Not 100% sure,
This is a male Widow Spider in the genus
Latrodectus, and it is most likely a Northern Black Widow, Latrodectus variolus, based on photos posted to BugGuide.

Male Widow Spider

Letter 3 – Male Black Widow and Bolas Spider Egg Sacs

Albino Widow and Idunno
We live within 25 miles of Los Angeles. The “egg sacs” on the bottom of the lawn chair were found on the 4th of July. The closest one looks like it has legs, but I never saw anything move.

We left it unprotected and I think the gardener destroyed them. I’ve shown the picture around without a hint. And this is the second time we’ve found one of these. Looks and acts a lot like a Black Widow, but the color…
Thanx for this website!
jared

Hi Jared,
Here is what Eric Eaton has to say about your bachelor: “It IS a widow, probably an immature, or a male, or both. Widows are “born” white, with scattered darker markings. They darken as they age.

Males of some species retain the pale color into adulthood (they reach adulthood much faster than females, and are less than half the size of females at maturity).

The egg sacs shown with the widow are NOT Achaeranea tempidariorum, but not sure exactly what they are. Very strange, but distinctive and probably identifiable. Eric ”

Update:  May 25, 2014
We just approved a comment from Heather indicating that the Egg Sacs are Bolas Spider Egg Sacs.  We found images on the Natural History of Orange County website that confirms Heather’s identification and indicating that the species is 
Mastophora cornigera.

Letter 4 – Male Western Widow

What’s that spider?
I found this this little spider crawling on my 9 year olds bike here in Placentia, Cal. and was trying to figure out what it was. I searched thru your spider images but didn’t see one quite like it. It’s about 1/2 inch long including the legs.
Thanks
Rus

Hi Rus,
Nice photo of Latrodectus hesperis, the Western Black Widow, a male specimen. Males are not as well recognized as females, but their bite can also be dangerous.

Letter 5 – Male Widow Spider

here I go again
Thank you for the help with the beetle I.D. I asked for earlier. Now I have another. While digging around in the backyard (Fort Gordon, Georgia) I came across this beautiful guy. Any ideas?
Stefan

Hi Stefan,
This diminutive beauty is one of the Widow Spiders in the genus Latrodectus. Based on the enlarged pedipalps, it is a male.

Immature females and males often have similar coloration, but the pedipalps easily distinguish the males. According to BugGuide, the male spider is harmless, but it doesn’t indicate if they bite, just that they are harmless.

Letter 6 – Maligned Black Widow

Black widow spider picture
Hello there,
I found this Black Widow spider in my back yard the other night. To be quite honest, “I hate these things with every ounce of life in me!” They are the only things that really make my skin crawl.

With that said, I took this picture with my new camera and I was very surprised how well it came out. The picture is so good; I thought I would share it with you and the world. I hope you like it, if so please post it on you web site. My name is Mike and I live in Southern California .
Thanks

Hi Mike,
While we respect your dislike, we have learned to live in harmony with Black Widows in our Southern California offices.

Letter 7 – Northern Black Widow

Black Widow spider
Location: Barnegat, NJ
May 9, 2012 10:10 pm
We have found many Black Widows in our back yard, and even though we have 2 medium sized dogs, we are not concerned at all with the spiders since we learned how much they just want to be left alone and are not aggressive at all.

It seems like you mostly have to be looking for them in order to find them (under rocks, logs, etc.), and even when they are discovered, they have to have their lives threatened before they’ll bite. Otherwise, they are incredibly docile.

The 1st Black Widow spider we found was still a juvenile, and still had the red dots down its back. We kept it in a container for just one night before we released it into the woods far away from the neighborhood the next morning. In just that one night, it shed its exoskeleton! We kept the shedding in the container.

About 2 months later, right around Halloween, we found a very large mature Black Widow spider, and did the same thing — kept it in the same container as the 1st one before releasing it into the same woods later on that day. Before releasing both spiders, we (of course) took pictures.

The picture I’m attaching is of the 2nd, larger spider, with the shedding of the younger, smaller spider dangling above it. We were fascinated to see how you can easily see the outline of the fangs on the shedding!

We have since tried to let people know how these spiders get such a bad rap for unfair reasons, but not many are convinced. Fear has been ingrained deeply in some!

Hope you enjoy this macro shot for your wonderful site!
Signature: Thy Cavagnaro

Northern Black Widow

Hi Again Thy,
Thank you for sending in your photo of a mature Northern Black Widow.  Like your previous submission, we are tagging this with the Bug Humanitarian Award.  You are correct.  Black Widows are docile spiders that rarely leave their webs and they are not aggressive. 

They are feared and reviled by so many folks who would much rather exterminate than learn anything of their habits.  We once had one living near an outdoor light outside of our Los Angeles office and the spider would hide by day and come out at night where she fed on moths and other insects attracted to the light.

Letter 8 – Northern Black Widow, presumably male of the species

Subject:  Male Northern Black Widow?
Geographic location of the bug:  Magnolia, Delaware
Date: 01/02/2019
Time: 04:51 PM EDT
Your letter to the bugman:  Was able to find similar markings on pictures making me think this is a Northern Black widows, but nothing exact. Found in September, near a storage shed under a damp piece of timber.
Thanks.
How you want your letter signed:  Don Sloan

Northern Widow, male or immature female?

Dear Don,
We agree that this is Widow, and considering your location, it is presumably a Northern Widow,
Latrodectus variolus.  We cannot state for certain if it is an immature female or a male, but we would lean towards immature female.  Here is a BugGuide image for comparison.

Letter 9 – Northern Widow with Egg Sac

How big can black widows get?
Location: Sanford, NC
August 26, 2011 10:52 am
My husband was moving the basketball hoop in our yard (getting ready for the huricane), when we spotted this huge spider with an even bigger egg sack. she was the size of a dime and her sack more like a nickel. The biggest spider and sack we had ever seen. Under the hoop was also 3 other large sacks and 2 smaller black widows.

We did exterminate them, as our 4 children & small dog play in that area with no shoes on. My question is: how big can black widows get? I did not know that they got this large! Thank you
Signature: Keriann

Northern Black Widow

Hi Keriann,
The red spotting on the back of this mature Widow identifies her as a Northern Black Widow based on the information contained on BugGuide.  We have seen adult female Western Black Widows with abdomens nearly as large as a marble or a small grape. 

These are mature females that are most likely filling with eggs.  While we feel badly that you have exterminated several Black Widows from your basketball court, we fully understand your concern for your children and pets.  Black Widows are not an aggressive species, and they are rarely found far from their web, unless they have been disturbed. 

We once allowed a Western Black Widow to keep her web by our porch light.  We knew she was there and we were not concerned about getting attacked.  You would be much safer to fully educate the children regarding the dangers of being bitten by a Black Widow and ensuring that they learn to recognize them. 

If you killed three individuals in your yard, there are most likely more to be found in hidden locations and you will probably not be able to eliminate them all.  We hope Hurricane Irene steered clear of your area.

Letter 10 – Not True but False Widow

Hi,
Great site!
Have a question about black widows. When we lived in the New Orleans area, we saw several spiders that were black and shaped just like a black widow, but had red markings on the top side of the abdomen.
I have not been able to find anything online that resembles them , and thought you might be able to help.
Thanks,
Mary P

Hi Mary,
First, the red hourglass is on the under side of the abdomen. There is a spider known as the False Widow, Steatoda grossa. Both the true and false widows belong to the Comb Footed Spider Family Theridiidae.

The False Widow is a beneficial spider, reported to prey on its more poisonous relative. It also eats Sow Bugs. It is a hardier spider than the true Black Widow. We find them in our yard all the time, and will take a photo the next time.

Letter 11 – Possibly Male Black Widow

Subject: Please help! Fast!
Location: Southern New Meixco
October 25, 2012 3:27 am
Hello! I am curious to know what this spider is because it is in my Jeep and it crawled on me the other day. I am hoping its not piosionous because I have two small children who ride in my vehicle as well and I. Please help me in identifying it and what I need to get rid or it
Signature: Galen G

possibly Male Black Widow

Hi Galen,
Your photo is quite blurry and lacking in detail, so a definitive identification might be impossible.  With that said, this appears to be a male Black Widow.  The good news is that while females are considered the most venomous and dangerous spiders in North America, according to BugGuide

“Adult males are harmless. The male’s abdomen usually has red spots along the upper midline and white lines or bars radiating out to the sides. (The number of bars can indicate which species.) Males almost exclusively wander in search of females.”

Thank you. Yes I know it’s not the best picture but I snapped the picture and realized I should have just killed the darn thing cause it crawled fast away after the flash turned on. But again thank you! I will rip apart my jeep until this guy is found.
-Galen

Letter 12 – Prepubescent Black Widow

What spider is this?
I found this guy or gal lounging in my garage sink. I suspect it to be a widow of some sort because of the hour glass and the messy web. What do you think?
Rus

Hi Rus,
You have an immature Black Widow. Your photos show both the immature coloration and the distinctive hourglass. Great images.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

8 thoughts on “Black Widow Spider Male vs Female: Unraveling the Differences”

  1. I mostly agree, and I hope they did educate their children, but this will not prevent bites when the kids didn’t see the spider until it was too late.

    “Black Widows are not an aggressive species, and they are rarely found far from their web, unless they have been disturbed. We once allowed a Western Black Widow to keep her web by our porch light. We knew she was there and we were not concerned about getting attacked.” Yes, but the spiders are on/under the thing the kids are playing with (i.e. the hoop). While going to make a basket, they could accidentally come into contact with a frightened large black widow spider protecting her eggs. It’s the classic situation when this spider which normally avoids humans might bite. A porch light is quite different. They shouldn’t have to stop playing basketball just because a few spiders decided to make it their home uninvited. And how do you educate your *dog* or cat to avoid them?

    We should never kill or harm a living thing for no reason, and if something is not dangerous to us we should leave them alone, but these people did not go on a mindless slaughter by any means. They discovered they had spiders with a bite that can cause severe symptoms and can be life-threatening for children and small animals and chose the option that resulted in the fewest total deaths while decreasing their immediate risk. I’m a vegan, I believe all life is valuable and we should respect nature but I understand that sometimes we have to make sad/tragic choices to protect our loved ones and it doesn’t mean we’ve done something wrong.

    Reply
  2. I mostly agree, and I hope they did educate their children, but this will not prevent bites when the kids didn’t see the spider until it was too late.

    “Black Widows are not an aggressive species, and they are rarely found far from their web, unless they have been disturbed. We once allowed a Western Black Widow to keep her web by our porch light. We knew she was there and we were not concerned about getting attacked.” Yes, but the spiders are on/under the thing the kids are playing with (i.e. the hoop). While going to make a basket, they could accidentally come into contact with a frightened large black widow spider protecting her eggs. It’s the classic situation when this spider which normally avoids humans might bite. A porch light is quite different. They shouldn’t have to stop playing basketball just because a few spiders decided to make it their home uninvited. And how do you educate your *dog* or cat to avoid them?

    We should never kill or harm a living thing for no reason, and if something is not dangerous to us we should leave them alone, but these people did not go on a mindless slaughter by any means. They discovered they had spiders with a bite that can cause severe symptoms and can be life-threatening for children and small animals and chose the option that resulted in the fewest total deaths while decreasing their immediate risk. I’m a vegan, I believe all life is valuable and we should respect nature but I understand that sometimes we have to make sad/tragic choices to protect our loved ones and it doesn’t mean we’ve done something wrong.

    Reply
  3. My ex was bitten by a brown widow after moving a ladder the widow had nested in, with egg sacs. She was apparently very protective of the sacs (they are actually described this way by entomologists), and bit my ex twice on his calf. His arms seized up repeatedly and he felt really ill on the first day. He was sick for about two weeks, in all, mostly feverish, with heart palpitations. He did not go to the doctor, despite my advice.

    He said he felt “mini-heart attacks” for about a year afterwards.

    Not realizing the nesting problem, he stashed the ladder on our front porch. I ended up extermniating at least couple of hundred brown widows from the front yard area over the next few years – 60 the first night, 40 the second night, and so on. It took about 7 years of this to finally extinguish the breeding.

    Reply

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