Petrobia mites can be recognised by their reddish-brown cuticle, dark body contents and the first leg pair being very long.

Each leg ends in pad-like claws and a hooked (uncinate) empodium with more than 1 pair of tenent hairs.

The prodorsum of the body has three pairs of setae (ve, sci, sce) and there are no prominent lobes over the gnathosoma.

[5] The genus is usually divided into three subgenera: Mesotetranychus, Petrobia and Tetranychina (sometimes one or more of these are considered separate genera).

[8] Several Petrobia species are polyphagous plant pests, meaning they attack a wide range of plants:[5] These 34 species belong to the genus Petrobia: Data sources: i = ITIS,[9] c = Catalogue of Life,[1] g = GBIF,[2] b = Bugguide.net[3]