The silky lacewings are distinguishable in their adult stage by their spectacularly patterned and pubescent wings, broad wing shape, dense venation, and the presence of a vena triplica (the apical fusion of three veins in the hindwing).

In particular, the spoon-winged laceflies (Nemopteridae) seem to be very closely related to the silky lacewings.

The fossil family Osmylopsychopidae was - as indicated by their scientific name - initially believed to be intermediate between the Psychopsidae and the Osmylidae.

But actually these similarities are due to plesiomorphies in the first case, and simply misperceived in the second; the osmylopsychopids are one of the basal lineages of the Myrmeleontoidea as traditionally defined.

[citation needed] Silky lacewings were especially more diverse from the Triassic period to the Tertiary than in modern times.