Any small flat degenerate wingless neuropterous insect of the group Mallophaga, parasitic upon birds and mammals and feeding upon dermal excretions or upon the softer parts of hair and feathers. The term "biting-lice" is sometimes given to these parasites, in allusion to the mandibulate character of their mouth-parts, which serves to distinguish them at once from the true lice of the order Rhynchota in which the jaws are haustellate.