What do black widow spiders look like?
There are actually five different species of black widow spiders in the U.S. Four of these are native, while one is an introduced species. They include:
- Red widow
- Brown widow (invasive)
- Western black widow
- Southern black widow
- Northern black widow
These spiders are part of the family of comb-footed spiders and spin messy, tangled cobwebs, particularly in corners and under eaves. They like undisturbed places that protect them from the elements.
Black widow spiders are often identified by their dark brown to black coloration, as well as the telltale red hourglass symbol on their abdomen. However, there is considerable variety within species: one red widow may have a partial hourglass while another may have no red pattern at all. In addition, males will often have a different pattern than females. Even more challenging is the fact that the hourglass shape is only on the underside of the abdomen.
In general, the different widow spiders will have these characteristics:
- Western black widows have complete typical hourglass shapes that will be red or yellow. As the name suggests, they are found in the western United States. Males are usually light brown while females are shiny black. This species of widow can eject sticky silk directly at their predators.
- Southern black widows have a full hourglass with the bottom half thicker than the top half. Males will almost always have a full hourglass shape. They are found in the southeastern U.S., but as far north as Ohio and as far west as Texas. Females can live up to three years.
- Northern black widow territory ranges up to Massachusetts and even overlaps with the southern black widows. With this species, the hourglass is often split or partial; their coloring is more dark brown than black.
- Red widows have bright red legs, as well as brown to black abdomens. The hourglass is often partial, split or entirely absent. They will also have red, black and orange patterning elsewhere on the abdomen. Native to central and southern Florida, red widows are listed as a threatened species in the U.S.
- Brown widow (invasive) spiders have a reddish shape that looks like a wide hourglass, although the color typically ranges from yellow to dark orange. Males will have variations in the color and shape of their pattern. Their legs are striped, differentiating them from the other black widow species. They contain their eggs in a spiky ball-shaped sac, which is said to look like a sandspur. In just one season, a female can lay 20 egg sacs with approximately 150 eggs per sac. Recent research suggests that brown widows are out-competing the native black widow in the western U.S.
Where do black widow spiders live and eat?
Like many species of spiders, black widows are solitary and mostly nocturnal. They prefer mostly undisturbed areas and, outdoors, they can be found in and around sheds, outbuildings, heavy brush, small animal burrows and other cozy areas. Before the advent of indoor plumbing, they were often found in outhouses, eating the insects that were attracted to the space. They can creep closer to homes and be found under decks and eaves, in corners, and even under furniture and other household items.
As with other spiders, black widows feed on insects, other arthropods, and sometimes small reptiles. Despite their name and legends, the females rarely eat their male mates. They are beneficial because they eat many pest species. Their webs are quite sticky and easily catch flying and crawling insects which they quickly bite, inject with venom, then eat.
To capture their prey, adult female black widow spiders do have venom, while males and immature females are harmless. This venom can cause latrodectism, an illness involving pain, vomiting and muscle rigidity, which may require medical attention. The most common reaction is pain and less than 1% of bites world wide result in mortality. These spiders are not aggressive and will only bite when they are threatened and cannot run away. People do get bitten when they put on shoes or gloves that have sat outside and a black widow has made it her home.
If you think you have been bitten by a black widow spider, see a medical professional. If safe to do so, collect the spider in a container, so it can be identified properly and the right treatment can be administered. Despite many pictures on the internet, it is nearly impossible to tell from the wound if a bite has come from a black widow. Black widow spiders can bite without injecting venom; and even when they do inject venom, not everyone reacts to it the same way. Also know that infections may occur at the site of the wound.
How to prevent black widow spiders
One important way to prevent black widow spiders is to limit their habitat. Since they prefer areas that are sheltered and protected by vegetation, fallen trees, stones and other debris, removing those items makes their environment less hospitable. Removing branches that touch the house and reducing the vegetation around the foundation can help as well. If they have no place to hide and safely build their webs, they will find other areas that are better suited to them.
The option is reduce their food source. By reducing the number of insects around the house and yard, you can encourage the spiders to visit other areas where they might find food. This approach also helps reduce other pests around the home.
Lastly, knock down any webs you see. Spiders put a lot of energy into building their webs, so if they are constantly getting brushed away, the spiders will go to a better location. Make sure to take precautions when interfering with webs. Wear gloves, long sleeves, pants, and shoes.
When preventing spiders inside the home, seal up all openings that connect the inside with the outside. These spiders can climb well, so check all around doors and windows for cracks to be sealed. Inspect any lines or conduits, particularly with HVAC systems, to ensure they are sealed. Also, watch attics and crawlspaces, sealing them off from the living spaces. Since these spiders are solitary by nature, it is rare to find infestations of them indoors — although it can happen if a female with an egg sac gets in and all the eggs hatch.
Treatments for black widow spiders
Most store-bought liquids and aerosols do a good enough job of killing spiders they contact. However, if they do not make direct contact with the spider, any residue left behind is not very effective, as they spend most of their time in their webs, versus crawling across residue. However, insecticidal treatments may decrease the number of nearby insects, thereby limiting the black widows’ food sources. Much like granular products, insecticides won’t impact the spiders themselves, but will impact their prey. There are no bait treatments for black widow spiders, either. As with any treatment, make sure to read and follow all label directions.
Indoors, spiders can be carefully collected in a cup and either released outside or disposed of.
Finding a specialist for black widows
Finding black widows or other spiders in your home can be downright scary. The good news is that they can be easily controlled with help from a trained pest professional. If you are concerned about spider control for your home, please give At Home Pros a call. When it comes to pest control and other home service professionals, At Home Pros can connect you to the top-rated home service providers in the area, no matter where you live in the United States.
Learn how much you should be paying for pest control near you.