Pthirus pubis, commonly known as pubic lice or crab lice, are small parasitic insects that infest the human pubic area. They are about 1-2 mm in size and have a crab-like appearance, which is how they got their nickname. These lice feed on human blood and can cause itching and discomfort in the affected area. Pubic lice are typically transmitted through close physical contact, often during sexual activity. They can also spread through sharing personal items like towels or bedding. While they are not known to transmit diseases, their presence can lead to secondary infections due to scratching. Treatment usually involves topical insecticides.