_Sub-Order 1, Planipennia_, or true Neuroptera.
Metamorphoses complete, larvæ, mostly terrestrial.
_Sub-Order 2, Trichoptera_, or hairy-winged Neuroptera.
Metamorphoses complete, larvæ aquatic. Wings of Imago clothed with
hairs.
_Sub-Order 3, Pseudo-Neuroptera_, or false Neuroptera.
Metamorphoses incomplete.
The most important distinction between the first two groups and the
third is that the former undergo complete metamorphoses, whereas in the
latter the transformations are incomplete or imperfect. The latter for
this reason are often classified as a separate order.
The _Trichoptera_ are also placed by some entomologists in a distinct
order, on account of the peculiarity in their wings being clothed
with hairs. They, however, present so many points both in habits and
structure, analogous with the true _Neuroptera_, that we have retained
them as a sub-division of the Order.