Black Widow Look Alikes. If you have ever heard of a black widow spider, then you probably think of a dangerous spider. In fact, it is only the female black spider that is dangerous to humans.
It can be confusing as there are a number of spiders that look just like the black widow, some are completely harmless, while others are also considered dangerous.
Wondering if it was a black widow you saw? Continue reading to find out more.
In the spider world it appears there are three types of widows; true widows, false widows and false false widows. You could argue that a true widow is a false false widow, but that’s going around in circles!
What Are Black Widow Spiders?
Black widows are spiders found across the world and are one of the most venomous species in the United States. Even though black widow bites are rarely fatal and only happen when you provoke a spider, they can still cause a lot of pain and make you extremely sick.
If you’re worried about a spider you found near your home, there are many ways to tell if you’re dealing with this dangerous species.
We’ll start with some distinguishing physical features to look out for and move on to information about the spiders’ webs and where to find them.
Characteristics
-Comb foot: An important characteristic of the black widow spider is its comb foot. This row of strong, curved bristles is located upon the hind pair of legs and is used to pitch silk over captured prey.
-Shy: Black widows are shy in nature. They are solitary, socializing only during copulation.
-Nocturnal: Black widows are nocturnal and spin webs during daytime.
-Hang upside down: They can sometimes be seen hanging upside down in their web, exposing a telltale hourglass abdominal marking.
In North America, there are a number of black widow species:
-Southern black widow (Latrodectus mactans).
-Western black widow (Latrodectus hesperus).
-Northern black widow (Latrodectus variolus).
Female black widow spiders are the most dangerous and are easily identified by the red hourglass on her belly with a shiny black body.
Males, on the other hand, have red and yellow bands and spots on their backs. They also have longer legs and smaller bodies.
Juveniles look like males.
How To Identify A Female Black Widow Quickly
-Bright red hourglass marking on the underside of the abdomen.
-Shiny black in color.
-Measures up to 13mm in body length, excluding the legs.
How the Black Widow Spider Received its Name
The black widow spider received its name due to a story about its mating behaviors. Courtship begins when males go out in search of receptive females.
Upon approaching a web-spinning female, the male spider will wait for an indication of her willingness: females interested in mating remain still, allowing males to inseminate them.
As the story goes, following insemination, female black widow spiders kill and feed upon their mates. This story led to the black widow’s name. However, it is a misconception that all female black widows kill and consume their mates. Rather, this behavior is typically only observed in captivity.
The black widow contributes to the balance of the ecosystem by consuming insects such as flies and mosquitoes. It also controls crop pest populations, feeding on pests that defoliate plants, including locusts, grasshoppers, beetles and caterpillars.
Black Widow Bites
If bitten by a female black widow, you can experience some unwelcome side effects due to her toxic venom.
Symptoms include nausea, dizziness, sweating, pain at the bite site, high blood pressure, chest pains, salivation, and headache. In addition to this, other symptoms include itching, rash, eye-watering, problems breathing, and swollen eyelids.
People might develop many different symptoms after getting bitten by a black widow spider. Some of these symptoms might be mistaken for the symptoms of another disease, especially if the patient in question has a tendency to get sick.
In the event you think you have been bitten by a black widow, it’s recommended you seek urgent medical treatment at your closest emergency room.
If there is someone with you, ideally they should capture the spider in a jar and take it with you to the emergency room.
Appearance
-Hourglass marking: Black widows are identified by red hourglass marking on the underside of their abdomens. This marking is bright red and signals danger to predators and attackers.
-Color: Black widows are shiny black in color.
-Size: Most black widow spiders’ bodies are 3 to 10 mm in size. Females are larger than males and can measure 13 mm in body length.
Where You Can Encounter Black Widow Spiders
Black widows are usually found where there is sparse vegetation, hollow logs, and piles of debris.
They are seldom encountered indoors, though they may be brought into the home in firewood or other items that have been sitting outside.
These are nocturnal spiders, that will hide in their nest during the day. At night they prowl for food on their webs, hanging upside-down waiting for prey to pass by.
Black widows are almost everywhere in the United States.
Northern black widow spiders are reported in northern states such as North Carolina, South Carolina, Virginia, Maryland, Missouri, New Jersey, Texas, Kentucky, Arkansas, New York, Pennsylvania, Illinois, and more.
As in the below map, southern black widows are often reported in the southeast states such as Texas, Florida, Oklahoma, Louisiana, Alabama, Georgia, Mississippi, South Carolina, North Carolina, Virginia, and more.
Western black widow spiders are often found in California, Texas, New Mexico, Arizona, Nevada, Oregon, Washington, Utah, Idaho, Colorado, and more.
Spiders That Look Like Black Widows but Aren’t
Brown widow spiders (Latrodectus geometricus)
Immature brown widows and western black widows look very much alike when they are young. Adult brown widow females have a reddish hourglass marking on the bottom of the abdomen, but are often more of a tan or dark brown color rather than black.
However, this color distinction is not always easy to see. A black widow with an hourglass marking will display the shape prominently, whereas brown widows will have a less distinctive, duller marking. Also, brown widow bites are less painful than the bite of the western black widow.
Scientific name: Latrodectus geometricus.
Common name: brown widow, brown button spider, grey widow, brown black widow, house button spider, geometric button spider.
The brown widow is related to the black widow but is not as dangerous. Brown widows have black and white patterns on the side of their abdomens and an orange to yellow hourglass shape.
These spiders are smaller and lighter in color than the black widow with stripes on the legs. If you are bitten, their bites are painful but are not considered dangerous.
Brown Widow vs Black Widow
The hourglass shape is orange to yellow in color and not bright red They have black and white on the side of the abdomen, the black widow is completely black and shiny Smaller in size than the black widow
Black House Spider (Badumna insignis)
The black house spider is a dark colored spider, more bulky and awkward in appearance than widow spiders. Both males and females have dark brown legs and a gray abdomen with light markings on the top of the body. These spiders can bite if disturbed, but are not aggressive. They usually try to escape rather than bite.
-Scientific name: Badumna insignis.
-Common name: black house spider, common black spider.
The black house spider female can grow to 18mm in body length with a 30mm leg span. They have a dark brown to black head space and legs with a charcoal gray abdomen, along with being covered in velvet hair.
While they are venomous, they are not considered dangerous with bites being rare. If you are bitten, you can expect pain with localized swelling.
Black House Spider vs Black Widow
-Larger in size, up to 5mm larger than the body length of the black widow.
-Dark brown to black head space with charcoal gray abdomen.
-Covered in velvet hair.
-No red hourglass on the underside.
Noble False Widow Spider (Steatoda nobilis)
This spider is somewhat rare in the United States, but is found in California. The adult female has a bulb-shaped abdomen much like the widow spiders.
But the abdomen is brown and has cream colored markings similar in shape to a skull. Bites are very rare. Symptoms are minor and discomfort due mostly to the pests large fangs.
Common name: (noble) false widow.
Noble false widows are the largest in the false widow species and are often found near homes. They have dark brown on the front of their bodies and their legs. The large bulb-shaped abdomen can vary in cream with dark brown, sometimes there are very few markings if any.
Bites from the noble false widow are rare, they are not an aggressive species. They grow to a similar size as the black widow, of up to 14 millimeters.
Noble False Widow vs Black Widow
Rather than being shiny black, these spiders are dark brown with brown legs and cream to brown markings on their abdomens.
Red widow (Latrodectus bishop)
Adult female red widow spiders are reddish-orange, with reddish colored legs and a black or dark colored abdomen. The top of the abdomen usually has rows of red or orange spots outlined in white or yellow. Females lack a complete hourglass shape on the underside of the abdomen. Instead, they usually have one or two small red marks that look somewhat triangular.
Common name: Red widow.
Red widows are endemic to central and southern Florida, where this spider prefers a sand dune habitat. They have an orange to red head space with a black abdomen, that has yellow rings that outline a row of red spots.
The legs are red. They do not have the famous red hourglass on their underside, this is replaced with two small red marks. This is considered a venomous spider, but there are no bites recorded as it seldom comes into contact with people.
Red Widow vs Black Widow
-Red widow has an orange to red head space (cephalothorax)
-The black abdomen has yellow rings and red spots
-There is no red hourglass on the underside.
Domestic House Spider (Tegenaria domestica)
Adult domestic house spiders, also known as the barn funnel weaver spider, are reddish-brown and have a pale, freckled abdomen. Their bodies do not have the hourglass marking, vary from gray-brown to dark brown and have two dark colored stripes on the cephalothorax.
-Scientific name: Tegenaria domestica.
-Common name: barn funnel weaver, domestic house spider.
The domestic house spider has an elongated body with flattened head space. They are smaller than the black widow, growing to 11.5mm in body length.
They are dark orange to beige or brown in color with striped legs and two dull black stripes on their heads. The abdomen in brow, beige and gray mottling with a chevron pattern.
Domestic House Spider vs Black Widow
-Smaller in size, growing to 11.5mm.
-Dark orange, brown or beige in color, rather than the shiny black of the black widow.
-Striped legs, compared to the all-black legs of the black widow.
-Mottled abdomen.
-Chevron patterning on the abdomen
False Black Widows (Steatoda grossa)
This spider does not have the red hourglass marking and is a glossy chocolate brown colored spider. It shares the same rounded-abdomen body form and web-making traits as the true black widow spiders. However, this spider is slightly smaller than a mature western black widow spider. False black widows can bite if picked up or otherwise touched, but its bite is rare and is not considered a medically important spider.
Summary
The black widow is shiny black in color without any patterns, dots, or stripes. The underside of the female has a large red warning sign, an hourglass shape. These are the two things to bear in mind if you think you have been bitten or seen a black widow.
While there are many spiders you may think are black widows, the other spiders usually have different colors, they are different sizes and don’t have the bright red hourglass on their underside.
If you think you have been bitten, seek urgent medical treatment at your local emergency room and if you can, take the spider with you to help the medical team identify the best course of treatment