The Black Widow Spider
Latrodectus mactans mactans, commonly known as the black widow, is part of a family of spiders referred to as widow spiders. The black widow is not the only widow spider to be found in the United States, but is the most dangerous.
The female spider is black, with an hour glass-shaped red or orange marking on the underside of the abdomen, while the male is much smaller, brown, and has no marking. An adult female is between half an inch and one inch in length.
Only the female black widow has a venomous bite. The spiders bite only when disturbed, and most often when defending an egg sac. Black widows prefer to live in locations which are not frequently disturbed, such as woodpiles, garages, attics, and garden out-buildings. They may also live in foliage or garbage piles.
Black Widow Spider Bite Symptoms
Often, a black widow spider bite causes very little pain initially – someone who is bitten may feel only a pinprick. Generally pain and other symptoms develop within an hour of the bite occurring.
Symptoms may include pain, muscle cramping, headaches, nausea, vomiting, and anxiety. The site of the bite can be likened to a target, with a central reddened area surrounded by a ring which may be lighter than the person’s normal skin color. This in turn is surrounded by a reddened ring.
First Aid for Black Widow Bites
Being bitten by a black widow spider is painful and alarming, but one of the most important things to remember after being bitten is not to panic. Very often, a black widow spider will inject only a small amount of venom into the bite – in such cases the bite will be painful, but is not likely to be harmful.
Immediate first aid treatment includes washing the area clean with soap and water, and applying ice to help reduce inflammation.
A non-serious bite may be treated at home with regular application of ice packs. The wound should be kept clean and dry. Over-the-counter medications may be used for pain.
If someone who has been bitten by a black widow spider has severe pain, or is experiencing any other symptoms in addition to pain, emergency medical care should be sought. The bitten person may need treatment with antivenin.
Children, the elderly, people with known high blood pressure, and anyone with an acute or chronic illness, should receive emergency medical treatment, as they are more at risk of complications.
When in doubt, it is always better to err on the side of caution. If someone has been bitten and you are not sure how severe their condition is, seek medical treatment.
This information is for educational purposes only, and should not be considered a substitute for professional medical advice.
California Poison Action Line: Spider Bites
Jerry R. Balentine, DO, FACEP; Samuel M Keim, MD for eMedicine Health: Black Widow Spider Bites
Melissa Conrad Stoppler, MD for MedicineNet.com: Spider Bites
Sean P Bush, MD, FACEP for eMedicine.com: Spider Envenomation, Widow