The Genus Phthirius is better known as the pubic louse. This small, parasitic insect attaches itself to the pubic hair of humans in order to feed on their blood. While often referred to as the pubic louse, this insect also goes by other names, including crabs, cooties, and crab lice. The scientific name, Phthirius, comes from the Greek word phtheir, which means louse. The Genus Phthirius belongs to the family of parasites known as Pediculidae, which includes several other types of lice that infest humans and other mammals. While not particularly harmful, pubic lice can cause itching, irritation, and discomfort, especially in sensitive areas of the body.