Wolf spiders, Lycosa species, are very common spiders with over 3000 species distributed worldwide in a wide range of habitats. They do not build webs but rather, like wolves, are hunters chasing down their prey. They are large, hairy, and typically brown to gray in color with various markings and lines. As hunters, they have good eyesight with conspicuously large eyes. Some species prefer living in open, disturbed habitats, like lawns, gardens, and parks, so encounters with humans are likely. However, they are shy and typically run away when disturbed.

Lycosa venom is primarily cytotoxic. Venom of some species may contain histamine.

Envenomation by Lycosa species is typically benign, though there is a common belief that wolf spider bites can cause tissue necrosis like the recluse spiders. This idea is not supported by data from several studies. A bite from a wolf spider is typically painful and lasts only 10 minutes. Puncture marks with localized bleeding, swelling, and erythema might be evident, and there may be some itching at the bite site. Systemic symptoms are rarely reported and include nausea, headache, and malaise.