Most of us are scared of spiders – even if we don’t want to admit it. But there’s one spider that really terrifies us: the black widow. Not only does its name sound terrifying, but this creepy-crawly creature has a bite that can really do some damage.
Featuring shiny black bodies, this spider has a red hourglass shape on its back. This spider is so dangerous, it even tells you that you’re time is running out if you’re bit by one.
Knowing how to identify a black widow spider is life skill everyone should have. Let’s take a closer look at what this spider looks like, how it behaves and other interesting facts about the black widow.
Table of Contents
- Identifying the Black Widow Spider
- Black Widow Locations
- Are Black Widow Spider Bites Fatal?
- Black Widow Bite Symptoms & Treatment
- How to Keep Black Widow Spiders Out of the House
- Other Amazing Black Widow Facts
Identifying the Black Widow Spider
Commonly referred to as widow spiders, these spiders are a part of the Latrodectus genus, which contains 31 species distributed throughout the world. These species include North American black widows, the Australian redback spider and button spiders of Africa.
There are many different types of widows, including:
- Black widows
- Red widows
- Brown widows
1. Appearance and Size
Widow spiders can vary greatly in size, depending on the species. But females are typically dark in color with reddish-colored hourglass-shaped markings on the bottom of their globular abdomens.
Some females have a pair of spots or no markings at all. The female black widow can sometimes be paler brown and have no bright markings whatsoever.
Male widows usually have different shaped red or white and red markings on the top of their abdomens.
Black widows can vary in size between 3 and 10 mm, but some females can have bodies as long as 13 mm.
2. Habitats and Distribution
Black widows are found in warmer climates. They’re found in all four of America’s deserts, with several species found in North America.
They can also be found in southern Asia and Europe, South America, Australia and Africa.
These spiders prefer to live in dark, secluded areas away from humans, like under wood piles, underneath stones and inside crevices. Indoors, black widows will hide in dark places, like basements, garages, cluttered areas of the home and closets.
3. Diet and Feeding Habits
The black widow, like many other species of spiders, eats insects and other arachnids that get caught in its web. The female widow hangs upside down waiting for prey, which shows off her bright red hourglass-shaped marking.
Her red marking is a warning to predators that she is a toxic creature.
Interestingly, her markings do little to deter prey. Experts believe this is because of the differences in how insects and birds perceive color.
Along with other spiders, the black widow also eats mosquitoes, flies, beetles, grasshoppers and caterpillars.
Once the prey gets caught in the widow’s web, she wraps her meal in silk using her “comb feet.” Widow spiders, which are comb-footed spiders, then bite their prey and inject venom that liquefies the victim’s insides. Once the prey’s body becomes a pool of slimy goodness, the spider sucks up the fluid.
Black widow spiders, like many other types of spiders, have poor eyesight. When they perceive a threat, they lower themselves down to the ground using a line of safety silk. They rely on vibrations to know when prey is trapped or when a larger threat is nearby.
Although the black widow’s bite can be dangerous, it’s not an aggressive creature. They usually play dead or flick silk at predators before resorting to biting. Bites to humans are usually defensive in nature because the human accidently pinched or squeezed the spider.
Mating can be a deadly affair for male black widows. Females sometimes devour their mates after mating, which provides them with nutrients needed to fertilize her eggs.
Not all widow spiders eat their mates, and the frequency of sexual cannibalism really depends on the species. Most of the time, this behavior is observed in laboratory settings where the males cannot escape.
Widows mate in the spring and early summer.
When females are ready to mate, they coat their webs in pheromones (or sensing chemicals) that attract males. Think of these chemicals as a personal ad on a dating website. Her pheromones actually provide males with a lot of information, like her age, her virginity status and how hungry she is.
The virginity bit is important because the first male to mate with an “untouched” female gets to fertilize most of her eggs.
Males destroy part of the female’s web as part of the mating ritual. Experts still don’t know why they behave this way, but some speculate that they target parts of the web wither higher concentrations of her pheromones as a way to say: “hey, she’s already taken.”
Others believe males, which bundle female webs into their own silk, seal off her pheromones and maybe even add their own into the mix.
Experts also don’t know why females allow men to destroy her home – the place where she lives and catches dinner. Some think males are actually doing the females a favor by destroying her pheromone-drenched web. Once she’s mated, she no longer has a need to attract males.
Destroying the pheromone web allows her to build a new one that won’t attract males.
5. Male vs Female
Like with many other types of spiders, male black widows are significantly smaller than their female counterparts – but only in body size.
Males actually have much longer legs, and their legs have brown or orange markings on their joints. Some males also have white and red stripes on their abdomens. Compared to females, males have far more intricate patterns and colors.
6. Black Widow Webs
Females depend on their webs for survival and food. They also use their webs to house their egg sacs.
Widows will spin large webs at or around the ground in dark and undisturbed areas, in small holes or crevices, near building foundations, inside storage sheds, or around outdoor furniture. Webs can also be found indoors in crawl spaces and in basements.
Webs are usually irregular in shape, and their threads are very strong. In fact, the ultimate tensile strength of their fiber is similar to orb-weaving spiders, which have some of the most durable silk around. The widow’s silk is about as strong as steel wire.
A widow’s web looks tangled and uneven, but it’s actually a carefully planned and constructed design. Each web has three carefully constructed levels: the bottom level has vertical trap threads, the middle level has tangle threads, and the top level has supporting threads.
7. Reproduction and Lifespan
After mating, females began producing egg sacs, which are tightly woven cocoons in her web. Females protect their babies until they hatch.
Egg sacs can be tan, white or gray in color, and their texture is similar to paper. They can range anywhere between 12 and 15 mm in diameter. Sacs are either globular or pear-shaped, and they can contain hundreds of eggs.
Only a handful of babies survive because widows are cannibalistic in the early stages of their lives. In other words, they eat each other for nutrients.
Any spiderlings that survive go through several molting stages. Some will overwinter and emerge fully developed the following spring. As juveniles, these spiders look like miniature versions of their adult counterparts. They’re dark in color with bright markings.
Hatchlings leave the nest after a few days, during which they start ballooning. During the ballooning process, they start to release strands of silk into the air and are whisked away to new locations.
When they find a new home, they begin weaving their own webs and hunting their own food.
Male black widows only live a few months, but females can live for a few years. The average lifespan widows is one year.
Black Widow Locations
Black widows are found in several parts of the world. In the United States, they are most common in southern regions in dry and dark areas.
1. Northern Black Widow
True to its name, the northern black widow (known as Latrodectus various) is found in the Northeastern United States. From as far north as Canada to Florida and out west to Texas, this spider can be found in many parts of North America.
How did their distribution get to be so wide? These spiders are occasionally transported in shipments to states outside of their natural range.
Northern widows prefer to live in areas with hollow logs, stumps, sparse vegetation and debris. These spiders rarely enter human homes and buildings. But they may be brought inside in piles of firewood and other items that are brought indoors.
Female northern black widow spiders have shiny black bodies with rows of bright red spots on top of their abdomens. The bottom side of their abdomen has the classic red hourglass shape.
2. Southern Black Widow
The southern black widow spider is found in the southern United States. Latrodectus mactans is the most common species found in this region, and there are several species that live in this area.
Like their northern counterparts, they rarely venture indoors, but they can be found in basements, construction openings and garages.
Southern black widows are more likely to engage in a violent mating ritual (i.e. eating their mates), and they’re also shiny black in color with a red hourglass-shaped marking.
3. How They Got Their Name
The black widow spider’s sometimes-violent mating ritual helped give this spider its sinister name.
During mating season, males will seek out receptive females. When they find a web-spinning female, they wait for an indication that she wants to mate. If a female is interested, she will stay still and allow the male to inseminate her.
As you’ve heard (and we’ve discussed), females are notorious spiders that will sometimes kill and eat their mates after the deed is done.
Are Black Widow Spider Bites Fatal?
It’s a common misconception that black widow spider bites are a death sentence. Widow spider bites are rarely fatal, and only the very young and very old are at risk of death (and those allergic to spider venom).
Still, black widows are venomous spiders – and their venom is potent. In fact, their venom is 15 times stronger than a prairie rattlesnake. They are, without doubt, one of the most poisonous spider genera on the planet.
More than 2,000 people are bitten by black widow spiders each year, but most recover within a day if they get medical treatment. And not all bites inject venom, so some people experience no symptoms whatsoever.
Males and juveniles are harmless. Only female widows produce potent venom.
People rarely die from black widow bites. Fatalities were mostly reported in the early 20th century and came from the Mediterranean black widow.
Black Widow Bite Symptoms & Treatment
The biggest danger is the latrotoxin in their venom (a type of protein venom), which can cause systemic effects, like:
- Abdominal cramps
- Muscle pain
- Muscle spasms
- Difficulty breathing
The bite of a black widow feels like a pinprick, but pain quickly begins to set in after a few minutes as the venom spreads to different parts of the body.
Victims of a bite may feel pain for 12 hours or more, and the other symptoms may continue for several days.
Bite victims can be treated with Black widow antivenom to minimize the damage.
If you’re bit by a black widow, seek medical treatment right away. Along with antivenom, you may also be given pain medication to manage the discomfort caused by the spider’s bite.
Severe bites are usually treated with antivenin and muscle relaxants.
Do not attempt to treat a widow spider bite yourself. Go to the emergency room right away.
How to Keep Black Widow Spiders Out of the House
Spiders are notoriously difficult to keep out of the house, but here’s the good news: black widows rarely venture indoors unless they’re brought there.
Still, if you’re worried that these dangerous creatures might sneak into your home, there are a few things you can do to keep them out.
1. Seal Holes and Cracks
The most effective way to keep black widows and just about every other insect/pest out of your home is to seal up any holes or cracks that may allow them to enter your home.
Black widows can sometimes be found in basements, so check the foundation of your home and any basement windows you have for potential entryways.
Seal up any small cracks, crevices and holes with caulk and use foam sealants for larger openings.
Make sure you seal up any gaps underneath doors that may also allow black widows to migrate indoors.
2. Keep Your Home and Yard Clean
Black widows will stay away from your home if they don’t have a suitable place to build a nest.
If you have a basement or garage, clean up and make sure you don’t have a cluttered mess of boxes. Clutter and dark corners are perfect spots for black and brown widow spiders to build webs.
Along with your home, you also want to keep your yard clean. Remove debris, clutter, wood piles and old hollow logs that may serve as breeding grounds for these spiders.
Also, be careful when bringing firewood and other items indoors. These spiders sometimes hide in wood piles.
Other Amazing Black Widow Facts
- The black widow spider’s venom causes Latrodectism, which causes the systemic symptoms listed above.
- The Australian redback spider is also part of the widow spider genus.
- Female black widows are three times more venomous than males.
- Black widows turn their prey into pulp before eating them, as spiders can’t eat solid foods.