The black widow spider is probably the most venomous spider in North America. Black widows thrive in temperate climates, so they are most common in the south and western regions of the United States.
People may find them in grape vineyards, outdoor toilets, or in other sheltered areas where debris builds up. These areas are perfect for the spiders to build webs and trap prey.
The black widow is famous for its name, given because the female spiders are known to kill and eat males sometimes after mating. Its shiny black body is also easily recognizable.
People can easily tell it apart from other spiders because the black widow has a reddish hourglass-shaped mark on its body. It can also have red and white stripes or spots on the upper part of its body.
Although people often fear the black widow for its venomous bite, it is less deadly than many believe. A black widow’s bite can be harmful, but it is rarely fatal.
Black widow spiders are not often aggressive. They most commonly bite people out of self-defense. Some experts would call the spider shy, as it would rather choose not to bite humans.
“They have no reason to bite us unless they’re threatened,” says Catherine Scott, an arachnologist at Simon Fraser University in British Columbia, Canada, in a Live Science interview. “We pose a much greater threat to them than they do to us.”
Simply coming into close contact with a black widow isn’t necessarily dangerous. Their bite is usually defensive.
People are most at risk for getting bitten when they squeeze or pinch the spider’s body, according to one study published in 2014.
The authors found that even repeated poking was not enough to cause a bite, but accidentally sitting on or grabbing a black widow when reaching for something else can lead to a bite.
Nevertheless, it is best not to touch the black widow with bare hands, and the best way to avoid a bite is to avoid touching the spider altogether.
Anyone who has to be in contact with a black widow should try letting the spider move on its own, or use a dull object to lead it outside.
Children and older people are most at risk of death from a bite. These groups should avoid being in contact with black widows as much as possible.
All spiders have hollow fangs to inject venom into their prey. Most spiders’ fangs are not strong or long enough to break human skin. The black widow’s fangs are different, however.
According to the United States Office of Safety and Health Administration (OSHA), a person may notice some pain when the spider bites, or they may not notice anything at all. Sometimes, two red puncture marks will be visible.
Some people may not realize the spider has bitten them until later. But, 30 to 40 minutes later redness, swelling, and pain might start to radiate from the site.
According to the American Association of Poison Control Centers, not all black widow bites are venomous.
Firstly, only the females will bite. In addition, venom is precious to a spider. The spider will choose when to inject venom and how much, if at all. The black widow saves its venom for when it feels its life is in danger.
A nonvenomous bite may not cause symptoms. The symptoms of a venomous bite may not be visible at first, but they can develop later.
Along with some pain and swelling at the bite site, the following symptoms can occur with a black widow’s bite.
They may take several hours to appear:
- rash or itching
- severe stomach pain
- strong muscle cramps in the stomach, shoulders, and back
- intense chest pain and tightness
- nausea and vomiting
- teary eyes
- difficulty breathing
- increased blood pressure
The person should contact emergency medical services immediately.
OSHA note that pain may continue for 8 to 12 hours, but other symptoms can last for several days.
A black widow’s bite can be venomous, but many people experience few or no health complications.
In 2013, people reported around 1,866 black widow bites to the American Association of Poison Control Centers. Only 14 of them resulted in severe symptoms, and none were fatal.
However, a black widow’s bite can be life-threatening for:
- older people
- those with other health conditions
During pregnancy, a bite may cause contractions and labor to begin.
If someone begins to experience symptoms or notices they have been bitten by a black widow, they or someone who is with them should contact the emergency medical services immediately.
They may also be able to call a local poison center.
- The following information may be useful for doctors to know:
- the age and weight of the person with the bite
- how they are feeling and whether or not they have any other health problems
- when they were bitten
- where on the body the bite is
- a description of the spider that bit them
Apply first aid
If possible, people should apply first aid at home while waiting for medical help.
People should take the following steps, as far as possible:
- Wash the bite site with soap and water.
- Wrap ice or an ice pack in a clean cloth and apply it to the bite site. This can slow the rate at which the venom spreads through the body.
- If the area is not getting proper blood flow, reduce the amount of time the ice is applied.
- Raise the area where the bite is and keep it still.
- Apply an antibiotic cream or lotion to the bite to help prevent an infection.
- Take an over the counter pain medication for pain.
- Take an antihistamine for itching.
- Watch the symptoms for any worsening.
If possible, people should put the spider or any remnants of it in a secure container. Giving this to a doctor can help them to provide suitable treatment.
After arriving at the hospital, a doctor or nurse will take vital signs, including their temperature, blood pressure, pulse, and breathing rate.
In some cases, the doctor will order tests, such as:
- a urine test
- a blood test
- a chest or upper body X-ray
- an electrocardiogram (EKG)
The person may need:
- pain relief medication to treat the symptoms
- IV fluids
If someone is experiencing severe symptoms, the doctor may give them an antivenin.
This type of medication contains antibodies that help treat the effects of a poison. However, it can sometimes cause severe allergic reactions, so the doctor may prefer not to use it.
In 2011, authors of a case series published in The Permanente Journal noted that a new antibody based antivenom was being developed that should have a lower risk of sensitivity.
People with a heart condition may need to spend time in the hospital.
Black widow spiders do not usually live in people’s houses, but they are relatively common in the United States in yards, woodpiles, sheds, and so on.
They may also be present at campgrounds and other outdoor locations. People who work outside should be careful to avoid them.
Tips for reducing the risk include:
- shaking out all shoes, clothing, and blankets before use, especially if they have been in storage for a while
- applying insect repellant to clothes and shoes
- using gloves and clothes that cover the body while cleaning out woodpiles and outhouses
- looking behind any garden furniture before cleaning or sweeping
Severe symptoms will improve within a few days. Milder symptoms can last for a few weeks.
The individual will be able to go home as the doctor sees fit.
Even with treatment, a bite can be life-threatening for younger children, those who are already unwell, and older people.