The Brown Recluse Spider is another one of the most poisonous spiders. It is native to the United States. These spiders can be found in dark places. They don't like to be disturbed and will run as well, unless antagonized. You can often find them in dark corners and crevices, wood piles, newspaper piles, old clothes not worn lately, in chests, attics, basements, window cylinders, boxes, under rocks, under anything in dark places.

The recluse is also called the violin spider because of its distinctive "violin shaped" marking on it's back. It is usually between 6–20 mm, but may grow larger. It is brown and sometimes an almost deep yellow color and usually has markings on the dorsal side of its cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider. Colouring varies from light tan to brown and the violin marking may not be visible.

Though it rarely bites humans, this spider is known primarily for its venom, which occasionally produces necrosis at the site of the bite. As indicated by its name, this spider is not aggressive and usually bites only when pressed against the skin, such as when tangled up within clothes, bath towels, or in bedding. Its danger is primarily in tissue damage. Its poison kills the cells and tissue at the bite. After applying ice and alcohol, seek medical attention. Again try to safely contain the culprit for identification. The initial bite is usually painful, but it becomes very painful within several hours. Again this makes it more dangerous because the damage is being done.