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The Black Widow Spider

Larry Slawson received his Master's Degree from UNC Charlotte. He has a keen interest in reptiles, insects, and arachnids.

The deadly Black Widow Spider.

The deadly Black Widow Spider.

Introduction

Throughout the world, there exists only a handful of spiders capable of inflicting serious harm to humans. One of these spiders is the infamous Black Widow. Well-known for their dark coloration and potent venom, the Black Widow Spider is a remarkable species of arachnid with the ability to inflict life-threatening injuries to its unlucky victims. This article explores the Black Widow in-depth, providing its readers with an analysis of the spider’s behavioral patterns, venom toxicity, and general characteristics. It is this author’s hope that a deeper understanding (and appreciation) of this fascinating creature will accompany readers following their completion of this work.

Scientific Classification

  • Common Name: Black Widow Spider
  • Binomial Name: Latrodectus
  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae
  • Infraorder: Araneomorphae
  • Family: Theridiidae
  • Genus: Latrodectus
  • Species: 32 different species (described)
Black Widow Spider preparing to ambush prey.

Black Widow Spider preparing to ambush prey.

Black Widow Spider Characteristics

The Latrodectus, or Black Widow Spider, is a species of highly venomous spider from the Theridiidae family. In total, approximately 32 different species of Black Widow are believed to exist, worldwide, including the Southern and Western Black Widow varieties. Occasionally referred to as the “Button Spider,” Black Widows are relatively small in size (0.12 to 0.39 inches) with females often growing larger than their male counterparts (reaching sizes of approximately 0.51 inches in rare cases).

Taxonony

The Black Widow was first described in 1805 by Charles Athanase Walkenaer, with significant revisions being made to the specie’s profile in 1959 by Herbert Walter Levi. Levi chose to revise the spider’s profile due to the large number of anatomical variations he discovered in specimens from around the world. As a result of his efforts, scientists now recognize 32 different species of the Black Widow that can be found on every continent (with the exception of Antarctica).

Coloration

As their name implies, the Black Widow is traditionally black (or occasionally dark brown) in coloration, and possesses a reddish-orange hourglass that typically appears on its ventral region. While this marking is one of the most recognizable characteristics of the Black Widow, not all Black Widows possess this distinguishing hourglass (for reasons unknown). On rare occasions, a pair of red spots can occasionally take the place of the hourglass design as well.

Male and female Black Widows can also be distinguished from one another due to markings on the male’s dorsal (upper abdomen). These marks, which vary between red or white, often appear in the form of a single stripe, or a series of bars and spots. Likewise, females can often be identified due to their larger size, paler coloration (brownish-black), and because of the overall absence of markings.

Behavioral Patterns

Despite their fearsome reputation, the Black Widow is actually quite shy and will avoid human contact whenever possible. Although aggressive towards insect populations, the Black Widow is remarkably timid in the midst of humans and will only bite when it feels threatened. For these reasons, Black Widows and humans are capable of living in relative harmony with one another as long as both parties respect one another’s space.

How Strong is the Black Widow’s Silk?

In more recent years, scientists have discovered a number of remarkable features pertaining to the physical properties of the Black Widow Spider’s web. Tensile strength tests on the spider’s silk show comparable strengths to steel wire (of the same thickness). Scientists believe that the spider’s silk may one day be incorporated into military and police uniforms, as the lightweight silk could provide soldiers and officers, alike, with unparalleled levels of protection at a marginal cost.

Black Widow alongside egg sac.

Black Widow alongside egg sac.

Habitat and Distribution

As with most members of the Theridiidae family, Black Widows can be found predominantly in dark and undisturbed environments. Building a nest comprised of irregular-shaped fibers of web, the Black Widow often constructs its home near the ground in small holes or crevices that are either natural or made by various animals. For this reason, wood piles, brush piles, stumps, and vents are often prime avenues for the spider, as they provide the Black Widow with natural protection from predators and an avenue to hide from potential prey before striking. Barns, basements, and some garages also offer the dry and dark environments preferred by the Black Widow.

Currently, Black Widows are found throughout much of the world’s temperate zones including North and South America, Southern Europe, Australia, Africa, and Asia. In the United States, they can be found predominantly in the Southern and Western regions of the country, as the dry and warmer climate serves as a perfect environment to their specific needs.

Black Widow Spider Quote

"Consider the black widow spider. It's a timid little beastie, useful and, for my taste, the prettiest of the arachnids, with its shiny, patent-leather finish and its red hourglass trademark. But the poor thing has the fatal misfortune of possessing enormously too much power for its size. So everybody kills it on sight."

— Robert A. Heinlein

Prey and Natural Predators

Prey

The Black Widow Spider can often be found hanging upside down within the center of their nest as they await their prey. The spider’s web (or silk), which possesses a sticky-like residue and fibrous quality allows the Black Widow to rest at a safe distance from unsuspecting insects and bugs who cross into their vicinity. As insects enter the spider’s nest, they quickly become entangled in the Black Widow’s web. Before they can escape, the Black Widow quickly springs into action, biting and envenomating their prey before wrapping them inside a silky web. After prepping their meal, the spider then uses its large fangs to puncture their victim’s body in order to inject the insect with digestive enzymes that breakdown its body into a liquid state. This, in turn, allows the spider to literally drink its prey as it sucks the liquified compound through the original puncture site.

Common prey for the Black Widow varies significantly by location, but often includes an assortment of flies, grasshoppers, caterpillars, beetles, and mosquitoes. Due to their vociferous appetites, the Black Widow often plays a vital role in maintaining a sense of balance within local ecosystems, as they help to control insect populations. Without spiders, common pests (such as mosquitoes) would quickly grow out of control.

Natural Predators

Although Black Widows are commonly assumed to be predators in the wild, the spider faces a number of natural predators of its own. These include wasps, centipedes, and scorpions that are capable of subduing the Black Widow with relative ease. Large insects, such as the Praying Mantis, are also known to prey on the Black Widow as the toxins from the spider can be easily digested without causing harm to the mantis. To date, however, Blue Mud-Dauber Wasps continue to be the greatest threat to the Black Widow as the insect is known to actively hunt and sting spiders for quick meals.

Juvenile Black Widow Spider.

Juvenile Black Widow Spider.

Reproduction

Where Does the Black Widow get its Name From?

The Black Widow gets its name from the ritual of sexual cannibalism that is practiced by the species. During late spring, female Black Widows are known to attract males for mating. Following the reproductive process, however, the female suddenly turns on the male, killing and then eating her mate. Although many hypotheses have been put forward regarding this unusual ritual, the most accepted explanation for this behavior (termed “sexual cannibalism”) is that females require additional proteins for the birthing process, as well as the nearly 200 to 900 babies she will give birth to later. Males, therefore, provide a quick and easy form of food for the female.

Do Black Widows Lay Eggs?

Yes. Following mating (and the consumption of her male counterpart), the Black Widow constructs a paper-like sac for her eggs that is designed to protect the babies from outside elements (both predators and environmental conditions, alike). Egg sacs are usually beige-colored and reach approximately 1 to 1.25 centimeters in diameter. Average yield is 220 eggs per sac with each reaching a size of 0.88 millimeters. In rare cases, the number of eggs per sac have reached records of nearly 900.

Life Cycle

After laying the eggs, baby spiders will then hatch approximately 30 days later. Babies (or “spiderlings”) are usually white at birth, and “lack the hour-glass or spot patterns” displayed by adult spiders for several weeks (ufl.edu). Following in their mother’s footsteps, the babies are also known to practice cannibalism in their early stages of development with very few of the original spiders surviving into adulthood (which takes nearly three months to reach after birth). Cannibalism is crucial for the baby spiders, as their small size prevents them from actively hunting insects for several weeks.

During the months following their birth, Black Widow spiderlings will molt on several occasions until they gain their full coloration (and hourglass). Overall development of the baby spiders depends on a number of factors, including diet and overall temperature (ufl.edu). Average maturity rates for males is approximately 26 to 103 days, whereas females reach maturity at approximately 57 to 122 days after birth (ufl.edu).

What is the lifespan of a Black Widow Spider?

The overall lifespan of a Black Widow is based on a variety of conditions, including their natural habitat and gender. In perfect conditions, males are expected to live a maximum of 3 months due to the cannibalistic behaviors of the female and their smaller size. Females, on the other hand, can live upwards of 3 years.

Venom Characteristics

Despite their relatively small size, the Black Widow possesses a highly potent venom that contains a variety of neurotoxins; most notably, latrotoxin. In North America, the Black Widow is considered the most venomous spider on the continent, with a venom that is reportedly 15 times more potent than a rattlesnake. Fortunately for the spider’s victims, the Black Widow only injects small amounts of its deadly venom into prey; thus, greatly diminishing the venom’s effect on humans.

Black Widow Spider Bite Symptoms and Treatment

Initial bites from a Black Widow Spider are often painless in their beginning stages and are commonly described as a pinprick sensation. However, within minutes, the bites quickly become extremely painful for humans as the venom begins to spread throughout the body. Although rarely fatal (due to the small amount of venom injected in most bites), all bites should be considered medical emergencies due to the variety of symptoms that often follow.

Bite victims often experience severe muscle pain, followed by abdominal discomfort (nausea, cramping, and vomiting), as well as hyperhidrosis (extreme sweating), irregular heartbeats, hypertension, and muscle spasms. Symptoms usually present themselves for upwards of 3 to 7 days after the bite occurs; however, severe envenomation can produce symptoms that continue for several weeks. Although antivenoms exist to counteract the spider’s venom, they are rarely used due to the potential for serious side effects. For this reason, antivenom is usually only administered in cases of severe envenomation which occurs predominantly with female Black Widows (due to their larger size). As a result, bed rest, and palliative care are often the primary treatment provided by doctors and hospital staff.

Are Black Widows Dangerous to Humans?

Yes and no. While their venom is quite potent, a Black Widow bite isn’t likely to result in death for average-sized adults. However, it should be noted that young children (particularly toddlers), the elderly, and individuals with compromised immune systems are the groups most vulnerable to a Black Widow’s bite. While any suspected bite from a Black Widow should be examined by a medical professional immediately, individuals from these three groups (or their caregivers) should deem the bite as medically significant and life-threatening. Early identification of bites and seeking immediate medical treatment are the best recourse for Black Widow bites.

Bite Prevention

Most bites from the Black Widow occur when humans inadvertently disturb their nesting areas (i.e. by reaching into woodpiles, stones, or when rummaging through sheds or barns). To prevent bites, experts agree that the utilization of work gloves can go a long way in preventing bites and envenomation as the Black Widow’s fangs usually can’t penetrate the fabric. Individuals should also search through shoes before wearing them, and to exercise caution when searching through old boxes, bags, and cases.

Concluding Thoughts

In closing, the Black Widow Spider is a remarkable species of spider that continues to fascinate researchers around the globe. From its potent venom to its remarkably strong web, the Black Widow Spider is a unique specimen that demands both admiration and respect. With new and exciting studies already underway regarding the spider’s behavioral patterns, venom toxicity, and general traits, it will be interesting to see what new information can be learned about this fascinating animal in the years and decades that lie ahead.

Works Cited

Articles/Books:

Slawson, Larry. “The Top 10 Deadliest and Most Dangerous Spiders in the World.” Owlcation. 2020.

Soloway, Rose Ann Gould. “Black Widow Spider Bites Can Be Dangerous.” Black Widow Spiders. National Capital Poison Center, July 31, 2019.

"Southern Black Widow Spider." University of Florida. Accessed March 9, 2020.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2020 Larry Slawson

Comments

Larry Slawson (author) from North Carolina on March 10, 2020:

Thank you everyone! So glad you enjoyed!

Eric Dierker from Spring Valley, CA. U.S.A. on March 09, 2020:

Thanks Friend. I needed to know more about these friends. Spider season is down here now. No food no spiders.

Pamela Oglesby from Sunny Florida on March 09, 2020:

I do not want to get close enought to a black widow spider to figure out if it is a male or female. :)

Seriously, this is an excellent filled with facts about this interesting spider. You wrote an very goood article that gives us all the details about this spider.

Lorna Lamon on March 09, 2020:

I can't say I'm a big fan of spiders Larry, however, your article is so interesting and full of great facts. A pretty formidable spider, however, it has a certain charm with its beautiful markings. I was also impressed by the strength of its silk. An enjoyable read and an education.