Aplocera praeformata, known as the purple treble-bar, is a species of moth in the family Geometridae.

Its northernmost range is southern Finland and the Baltic States.

[5] [6] The subspecies Aplocera praeformata urbahni is found in Greece.

The forewings have a gray to blue-gray basic color.

The caterpillars are gray-brown, with a white side line and a dark lower edge.