Black Widow Spiders: How to identify and Avoid

Black widow spiders are the easiest spider in the world to identify. Unfortunately, black widow spiders are also the most horrifying spider to identify up close and personal. The fear of the hourglass-shaped spider’s bite is world-renowned throughout the temperate regains of the entire world.

In many articles on black widow spiders, the author suggests that the reports of their venom and the inherent dangers of encountering black widow spiders are deemed “over-rated.”

That’s not true. Indeed, the black widow spider is nasty and potentially fatal to young and elderly humans. Therefore, any helpful article will recommend they be avoided, and those who live where black widow spiders reside can identify and avoid them.

Related: How to identify and avoid huntsman spiders.

Related: How to identify jumping spiders.

Related: Biting Ants: Six-Legged Stingers Found in the States

Black widows
Black widow spider. Photo credit: Ondreicka

The black widow spider in North America can also be red (Latrodectus bishopi ) or brown (Latrodectus geometricus). Despite their color, female black widows have dark-colored and easily identified reddish hourglass markings on the central underside. Only the female has a bite hazardous to humans.

Black widow spiders: Fascinating facts.

A study conducted in the 1950s found that 80% of black widow spider bites happened to men, most of whom were bit on the penis. Ouch! Why? 

As reported in, “Most of the black widow bites that were reported happened in outhouses. 

“So black widow spiders enjoy dark, low-to-the-ground sort of places. They especially love to make their cobwebs between two objects,” she explained, adding that bugs and flies love the stink of outhouses and made their home in the privvy bowls.

“So putting your web there is excellent. So imagine this. It’s the 1950s. You’re a dude. You need to go number two. You make your way out to the outhouse. You sit down, and your junk hangs there.”

“And as it does, it hits the cobweb. And the usually non-aggressive black widow instinctually runs over and bites down on the new creature that has landed on its web.”

Since bathrooms began moving indoors, the problem (disproportionate targeting of men and penises) seems to have gone away. Their bites today are rarely fatal, with the majority resolving without treatment and others being treatable in hospitals. “

Need any more reasons to fear black widow spiders?

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Black widow spider venom.

Black widow spiders have a latrotoxin in their venom. The latrotoxin causes toxic effects in the vertebrate central nervous system “by depolarizing neurons, by increasing [Ca2+] i and by stimulating uncontrolled exocytosis of neurotransmitters from nerve terminals.” 

Indeed, black widow spider bites can be dangerous and may result in severe muscle pain, abdominal cramps, abnormal sweating, high heartbeat rates, and muscle spasms. These symptoms persist for at least a week but may last for several weeks.

In the United States, each year, about 2,200 people report being bitten by a black widow. Still, no deaths due to black widows have been reported to the American Association of Poison Control Centers since 1983

Even though black widow spiders are not aggressive and rarely bite humans unless startled or otherwise threatened, their venom is nearly 15 times stronger than a rattlesnake’s. It can cause muscle aches, nausea, and paralysis of the diaphragm, which can make breathing difficult, which, to small children, the elderly, or the weak, may be fatal.

Related: How to identify the Brazilian wandering spider.

Black widow spider Black widow spiders
Black widow spider with male and egg sac. Photo credit: Kostich

Black widow spider feeding and mating habits.

As bad as a bite from a black widow spider is to a human, procreating with a female black widow spider is potentially even more dangerous. Female black widow spiders sometimes kill and eat their smaller male mates. Hence the name widow.

Black widow spiders usually are quite reclusive and solitary. You’ll only see two of them together during the (dangerous to the male) mating ritual. 

Black widow spiders create webs that act as escapes from predators and traps for prey. They are built close to ground level inside storage areas like sheds or garages, outdoor furniture, or your home’s foundation. Indoors, they are made in basements, attics, and crawl spaces. 

While these large webs are designed to catch flies, beetles, grasshoppers, and mosquitoes, you can inadvertently stick your face or an extremity in one of these spaces while accessing them.

Black widow spiders trap and kill their prey in these webs, injecting digestive enzymes that liquify the food’s body and create edible fluids the spider can digest.

Related: Tarantula bites.

Related: Tarantulas: Appearance, diet, and mating.

Black widow mating ritual.

Black widow spiders mate in the late spring. The process begins when the males wrap sperm-soaked silk around their palps.

Spider palps are appendages of touch and are elongated leg-like structures, serving as secondary sex organs.

With its palps ready, the male will rely on chemical lures to locate available females. When he finds a suitable (preferably recently fed) female black widow spider, he will dance on her web and pluck at its strands to create a song of vibration.

Over time, he will slowly approach her and begin tapping her body. Finally, if all goes well, she will allow him to insert his sperm-covered palps into the reproductive opening on her abdomen.

The female will then create an eggs sac containing several hundred eggs. These eggs will hatch thirty days later, producing spiderlings.

Avoiding bites by black widow spiders.

If you live where black widow spiders live, you must double-check and shake out any clothing, boots, and blankets you use. Outside, you must keep your unprotected hands out of unchecked firewood stacks, leaf piles, and other stored materials. When cleaning outdoor furniture, be very careful before grabbing it and moving it. 

What does a black widow spider bite feel like?

Black windows spider bites can cause pain that peaks within about three hours. This pain is accompanied by nausea, sweating, a spike in blood pressure, and fever. 

If a black widow spider bites you, or you live where a black widow spider might bite your children, make sure everyone bitten gets prompt medical treatment.

Treatment for a black widow spider bite is best facilitated by killing and preserving the spider if possible. Indeed, don’t smash the spider to the point it is unrecognizable.

A doctor able to correctly identify the bite of a black widow spider will provide medications and an anti-venom that will relax your muscles and reduce your pain. The anti-venom will also counteract the venom injected by the spider.

As seen in The Black Widow Spider Bite: Differential Diagnosis, Clinical Manifestations, and Treatment Options: “Anti-venom administration reduced pain more quickly than in the placebo group in individuals with moderate to severe latrodectism. Anti-venin treatment had an adverse event profile similar to that of the placebo. A Phase III clinical will be required to further evaluate this antivenin.

Antivenin use requires definitive identification of a Latrodectus bite, and often patients often do not know they have been bitten.18,19,23-26 Managing such cases requires: 1) a high level of clinical suspicion, 2) a thorough patient history, especially concerning places where a bite could have occurred, and 3) knowledge of how a spider bite presents.18,19,23-26 Failure to recognize a bite and give appropriate treatment can result in significant patient morbidity.”

According to a 1992 study:

“Latrodectus genus spiders have been the leading cause of death from arachnid envenomation in this country. Five species are found in the United States, with at least one in every state except Alaska.

The most common are Latrodectus mactans and Latrodectus variolus, which are located abundantly in southern and eastern states. The venoms of Latrodectus sp are virtually identical and thought to act at the neuromuscular junction by binding to glycoproteins or gangliosides on the presynaptic membrane and opening cation channels.

Large quantities of acetylcholine then are released from the presynaptic neuron while the reuptake
of choline is inhibited simultaneously.

The result is pain and cramping of large muscle groups. Severe envenomations also have been reported to cause weakness, hypertension, priapism, and, rarely, death.“

What if my pet is bitten by a black widow spider?

In a study Black Widow Spider Envenomation, Dr. Michael Peterson, DVM, writes:

“Black widow spiders are found throughout the continental United States and north into the southern Canadian provinces. Male black widow spiders are of little medical importance. Female black widow spiders can be 20 times larger than males.

The female can be identified by the hourglass pattern, red or orange in color, on the ventral aspect of her shiny, globose black abdomen. Black widow spiders control the amount of venom they inject; an estimated 15% of bites to humans are non-envenomating.

Cats are very sensitive to the venom and deaths are common. Dogs have severe clinical signs but are considered more resistant than cats. A single bite is capable of delivering a lethal dose of venom to companion animals.

There are several toxic components consisting of five or six biologically active proteins. These include a potent mammalian neurotoxin called alpha-latrotoxin, which induces neurotransmitter release from nerve terminals. Acetylcholine, noradrenalin, dopamine, glutamate, and enkephalin systems are all susceptible to the toxin.

Onset of clinical signs usually occurs during the first 8 hours post envenomation. The condition is extremely painful in moderate to severe envenomations. Abdominal rigidity without tenderness is a hallmark sign of Latrodectus envenomation.

In cats, paralytic signs may occur early and are particularly marked. Hypertension is a significant threat. First aid is of no value in the treatment. The primary treatment for black widow spider envenomation is the administration of specific antivenin, which provides the most permanent and quickest relief of the envenomation syndrome, usually within 30 minutes of infusion.

The prognosis of Latrodectusenvenomation is uncertain of several days, and complete recovery may take weeks.”

How to Get Rid of Black Widow Spiders 

The best way to keep from being bitten by a black widow spider is to incorporate reasonable housekeeping measures and make proper and safe use of insecticides.

Basements, attics, and garages should be kept as clean and organized as possible.

Working in these areas, especially outside, should mean using personal protective equipment—gloves. 

If gloves are not a good black widow spider control option, you’ll find many store-bought options to eliminate these pests.

Insecticides and Pesticides for black widow spider control.

Dusting and liquid chemical insecticides will work best on black widow spiders. Dusts seldom cause issues for people, and liquids applied to webs are practical and direct treatments.

Dusting with a product like D-fence using a hand bellows to reach into voids behind electrical outlets, switch plates is a simple, effective way to reach the areas black widow spiders hide in your house.

Onslaught FastCap works well outside around livestock facilities and landscapes and has a treatment mixture for use as an inside broadcast.

Pyrethrin will destroy black widow spider egg sacs.

Other insecticides will help remove the food sources black widow spiders need. If you remove their food, black widow spiders will not inhabit an area.

Do you have an issue with other stinging or damaging ants? Read these suggested articles:

How to identify and get rid of fire ants.

How to identify and get rid of carpenter ants.

Beware of the red veil event ants.

How to get rid of harvester ants.

Using insect traps to control black widows.

Removing flies, moths, grasshoppers, and earwigs will reduce black widow spiders’ food sources. In addition, putting out traps for these pests will naturally reduce the likelihood that a black widow spider will choose to build her web nearby. 

Bug glue traps left in attics, basements, under stairs, or even outside under porches and decks will catch mice and insects foraging for food, often long before they select your home as a residence.

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Dennis V. Gilmore Jr.

Dennis V. Gilmore Jr. is a former Marine Sergeant and the author of several books, including two on night hunting coyotes and red and gray fox. He has written several hundred articles on predator hunting for

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