This tribe contains two families, one of which is represented in the
British Isles.
_Family 5, Psocidæ._--This is a family of small insects with simple
veined wings. They have a rather large head, and bear a pair of long
tapering antennæ. They are found upon trunks of trees, old palings,
walls, etc. They are very active in their movements, and generally
appear in the imago state about the end of summer or beginning of
autumn.
_Atropos pulsatorius_ is one of these. It lives in books and among old
damp papers, whence it is often called the "Book Louse."
[Illustration: Fig. 57.--Perla Bicaudata.]
[Illustration: Fig. 58.--Psocus Bipunctatus.]
They are also very destructive to collections of preserved insects and
plants. About thirty species occur in this country.
_Family 6, Embiidæ._--This family contains no representative in the
British Isles, and consists of a small number of almost exclusively
exotic species. Two species, however, inhabit the continent of Europe,
one of which, _Embia Solieri_, occurs in the south of France on the
Mediterranean littoral.
These insects are very closely allied to the _Psocidæ_ in their habits.