Body lice are tiny parasitic insects only about as big as sesame seeds, according to Mayo Clinic. The bugs don't stay on the skin but instead live in clothing and bedding. The lice crawl on the skin to feed on blood before returning to clothing.
The life cycle of body lice includes the nit, nymph and adult stages. The nits, or eggs, are often found in clothing seams and occasionally on body hair. The nymph is the baby louse that hatches from the nit. The adult louse is tan or grayish-white, states MedlinePlus.
Body lice spread from close contact with an infected person. Infested clothing or bedding can also spread the insects. The lice can only survive for about five to seven days if they fall off of a person, according to MedlinePlus. Washing clothing in hot water and bathing regularly can get rid of body lice.
Body lice leave bite marks on the body where they feed on blood. The most common locations are where clothing seams touch the skin, such as in the armpits, waist and groin, Mayo Clinic reports. The host sometimes develops a rash at the bite location. The bites also cause intense itching, which may result in sores where the person scratches.