Other lice that infest humans are the head louse and the crab louse. Other lice that infest humans are the body louse and the crab louse. Pediculus humanus is a species of louse that infects humans. Symptoms of crab louse infestation in the pubic area include itching, redness and inflammation. The causative organism is "Rickettsia prowazekii", transmitted by the human body louse ("Pediculus humanus corporis"). The larva of the fish louse has two main stages. Cymothoa exigua, or the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. The term nit refers to a louse egg or young louse. The biting louse "Trichodectes jacobi" is also known to infest polecats. The cause was a tiny louse, known as phylloxera, imported from North America. Individuals of a bird louse of the genus "Strigiphilus" were found to parasitize laughing owls. The crab louse can travel up to on the body. However, some true flies such as Hippoboscidae (louse flies) have become secondarily wingless. The crab louse can travel up to 10 inches on the body. It is sometimes called the common fish louse.