Male and female brown widow spiders build a single type of web, which looks like a tangle of silk. Spider silk is a strong material mainly made of amino-acids, small molecules that form proteins, such as fibroin. Sugars and lipids also are found in spider webs, but in much smaller quantities.
The tangled web of the brown widow is used to catch small insects, which are part of the main diet of the spider. When a insect gets stuck in the web, the brown widow kills it with venom and wraps it with silk. Later, the spider feeds on the insect by sucking its body liquids. The brown widow produces the silk in glandes linked to the spinnerets, which are special organs located in the abdomen.
As the name suggests, the brown widow spider is generally light to medium brown, but can vary from very light brown to almost black. It has an orange hourglass-shaped marking on its abdomen. The back has white spots while the sides have a few white lines; darker spiders often do not have these markings. Females are about half an inch in body length, while males are about half the size of a female.
The female brown widow can produce 20 egg sacs over a lifetime, which averages three years. Males have shorter lives, from six months to one year. Egg sacs are tan, made of silk and have pointed projections on their surface, which give them a tufted appearance. Females are sexually mature from four to eight months old, while males are mature about three months after hatching. Spiderlings emerge from the eggs in two weeks.