Pediculus humanus capitis by Des Helmore The<unk>  (Pediculus humanus capitis) is an obligate ectoparasite of humans.<unk>  lice are wingless insects that spend their entire lives on the human scalp and feeding exclusively on human blood. Humans are the only known hosts of this specific parasite, while chimpanzees host a closely related species, Pediculus schaeffi. Other species of lice infest most orders of mammals and all orders of birds. Lice differ from other hematophagic ectoparasites such as fleas in spending their entire lifecycle on a host.<unk>  lice cannot fly, and their short, stumpy legs render them incapable of jumping, or even walking efficiently on flat surfaces. The non-disease-carrying<unk>  differs from the related disease-carrying body<unk>  (Pediculus humanus humanus) in preferring to attach eggs to scalp hair rather than to clothing. The two subspecies are morphologically almost identical, but do not normally interbreed. From genetic studies, they are thought to have diverged as subspecies about 30,000–110,000 years ago, when many humans began to wear a significant amount of clothing. A much more distantly related species of hair-clinging<unk> , the pubic or crab<unk>  (Pthirus pubis), also infests humans. It is morphologically different from the other two species and is much closer in appearance to the lice which infest other primates.<unk>  infestation of the body is known as pediculosis, pediculosis capitis for<unk>  lice, pediculosis corporis for body lice, and phthiriasis for pubic lice.<unk>  lice (especially in children) have been, and still are, subject to various eradication campaigns. Unlike body lice,<unk>  lice are not the vectors of any known diseases, however rare secondary infections can result from scratching at bites.<unk>  infestations may be beneficial in helping to foster a natural immune response against lice which helps humans in defense against the far more dangerous body<unk> , which is capable of transmitting dangerous diseases.
Head louse
Body louse
Crab louse
Botfly
Pinworm 
Humouse
Mosquito
Bowl of Hygieia