Black Widow Spider

Theridiidae latrodectus [Various Species]

When taking on its usual appearance of a glossy black body with red hourglass, the female black widow spider is probably the easiest spider to be identified by people throughout the world. There are over 30 different species of 'widow' spiders, including the red-back spider of Australia. In North America, there are 3 major species of black widow: The northern black widow (latrodectus variolus), southern black widow (latrodectus mactans), and western black widow (latrodectus hesperus). For the most part, these three species are visually the same.

Identification Guide

• Primary Colors: A mature female black widow will be solid black, with red markings. The red may be variations of orange or yellow as well. A mature male black widow will have varying colors of brown and black throughout its body. The markings can be orange, white, and black.
• Body Characteristics: Not counting the legs, female black widows are around 1/2 inch in diameter, while the males are generally half that size. The female black widow has a glossy, solid black colored body. It is important to note the glossiness of the spider, as this is a very significant feature of a widow spider, aside from the obvious red hourglass shape underneath its abdomen. The male black widow will be much smaller than the female, but will have longer legs than the female in proportion to its body.
• Legs: The legs on a female black widow will be similar to the body, in that they are solid black and glossy. Tiny hairs may be seen, which are usually more dominant closer to the body. On a male, the leg color will not be solid. In fact you should notice stripes of brown to black or dark brown.
• Markings: The famous red hourglass is seen on the underside of the abdomen on a female black widow. This hourglass will not always be shaped exactly like an hourglass, but it will always be on the underside. It can vary in color with red and orange being the most likely, but yellows and whites can be seen. The male will have an orange stripe or vertical dots along the top of the abdomen, with other white markings along the sides.
• What to remember: Remember the glossy black, smooth texture of the female black widow. No one will forget the red markings, but keep in mind that many innocent orb weavers can appear like intimidating black widows to the untrained eye. I say intimidating, because when people see bright colored markings on a round "bubbly" spider, they often think of the highly toxic black widow.

Habitat and Spider Web

When an adult female black widow finds an ideal home location, it will remain there for most if not all of her life. The black widow spider catches its prey in an atypical designed web made of extremely strong silk. The web is usually placed low to the ground, and is around one foot in diameter. Black widows, when not resting or hiding in a secluded part of the web, are normally seen dangling with their belly facing up, exposing their hourglass marking.

Black Widow Spider Bite and Venom

Spider Identification.org is a resource designed for casual spider enthusiasts to help identify the spiders they see. We are not a health site, and only provide limited basic information on spider bites and venom. The black widow is considered the most poisonous spider in North America, so we find it important to briefly cover the important facts regarding black widow bites and their venom.

Black widow venom is a neurotoxin, affecting the victim's nervous system. The seriousness of the bite depends on where the bite is located, the amount of venom injected, and the age or general health of the victim before the bite. Black widows are not aggressive, and will only bite when provoked or when feeling threatened. Death is very rare, and occurs in less than 1% of bite victims, with mortality being greater in the very young and elderly. Symptoms can be severe, and MAY include nausea, severe cramping, perspiration, abdominal pain, weakness, dizziness, and chest pain. If you are curious about treatment options and advice, please speak with your health care provider.