Scabies rash. Red and inflamed skin on a man's scrotum. This skin disorder is caused by an infestation of the mite Sarcoptes scabiei. The female burrows into the skin and lays eggs. Newly hatched mites are transmitted by physical contact. The mite's burrows are usually found between the fingers and on the wrists and genitals. Red lumps also appear on the limbs and torso. Infestation causes intense itching, particularly at night. Scratching results in the formation of scabs and sores. Treatment includes applying an insecticide lotion to the affected areas.