These insects, which are known as "Bird Lice," were formerly placed
among the true lice, but they differ in the possession of biting
mouths, and in the diet to which such a structure adapts them.
A great number of these curious little insects have been recorded, and
they inhabit all parts of the world. They live among the feathers of
birds and the hairs of mammalia.
Almost every animal and bird is subject to these parasites.
The common fowl, duck, goose, game birds of all kinds, and pigeons,
are very commonly infested by them, as are also the dog, the cat, the
sheep, and the guinea-pig.
The two principal families of the _Mallophaga_ are the _Philopteridæ_
and the _Liotheidæ_.
[Illustration: Fig. 61.--Lipeurus Diomedeæ (Mag.)]