Species of this family tend to be heavy-bodied and long-winged, the wings held folded across the back of the body at rest.

They rarely display any bright colours, usually being mainly grey or brown, with the exception of the subfamily Dioptinae (Grimaldi and Engel, 2005).

The larvae of some species are truly extraordinary: That of the puss moth has a fearsome-looking "face" and two long whip-like "tails" (actually highly modified prolegs) and it rears both ends in a threatening display when disturbed.

Adults have tympanal organs on the metathorax that opens towards the top, and the tibial spurs have serrated edges (Scoble, 1995).

The Dioptinae, which was formerly considered a separate family, are colourful and fly by day, while the rest of the notodontids are nocturnal.

[3] Recent molecular research has stabilized and consolidated most of the constituent subfamily and tribal rank taxa.