A black widow spider survives on a diet of various insects and arthropods. Their meals include beetles, grasshoppers, caterpillars, cockroaches, and ants, among others. If a black widow makes its home indoors, it can be found in less-frequented and cluttered areas where it can find more insects to eat.
The web constructed by the black widow is intended to catch prey. When insects get caught in the web, the spider will wrap it in silk, then inject it with venom to kill it. The spider will also inject digestive enzymes into the insect to help soften it before eating it. In a human, this type of process takes place internally. After a black widow has consumed its prey, its body actually elongates as the stomach expands.
If prey is scarce, a black widow, like many spiders, is capable of surviving for many months without food, sometimes even as much as a year. The spider has internal cavities that are able to store remnants of food.