The ftirapteros ( Phthiraptera ) commonly known as head lice, are an order of wingless insects ( without wings in the adult, in this case secondarily lost ) hemimetábolos ( whose development consists of egg, nymph and adult stages several ) ectoparasites of birds and mammals, which includes about 3250 species. Their eggs are called nits, that lice stick to hair or feathers of their host. They affect all birds and mammals, with the exception of monotremes ( Platypus and echidnas ) and few eutherian orders, as the chiropteran ( 41 bats; and folidotos ( 41 pangolins;. To this order belong insects causing infestations of economic importance as the human scalp 40 louse; Pediculus humanus capitis, other lice that affect the human is body Pediculus louse humanus corporis and crabs pediculosis pubis ) which affect 40 cattle; Damalinia ( Bovicola. ) Bovis, Haematopinus haematopinus, Vituli vituli, Solenopotes capillatus ) and several species of " piojillos of 34 birds; that affect the laying ( as Menacanthus stramineus, Menopon gallinae ).