Bucculatricidae are considered a subfamily of the Lyonetiidae by Emmet (1985a) and Davis (1987a) but in accordance with the Fauna Europaea (2014)) they are treated here as a separate family (see also Seksyaeva, 1990a). The only included genus is Bucculatrix. Two biological differences are that the Lyonetiidae have an ovipositor and deposit their eggs within the leaf tissue, while Bucculatricidiae glue their eggs to the surface. Bucculatricidae have a characteristically ribbed elongate, white cocoon.
The mines always are corridors, and small, often very small. This partly is connected to the fact that only young larvae are miners; older larvae live free on the leaf, mostly causing window feeding.
Like in Nepticulidae the mines start at a well visible external egg shell, but the egg is not globular and shining, but rather oval, more flattened, and especially iridescent. Contrary to the Nepticulidae the prolegs have crochets. A final difference is that Bucculatrix larvae are remarkably slender. This makes that the frass-free larval chamber is more than three times as long as wide (like in Lyonetia); in nepticulids the larval chamber clearly is relatively shorter and wider. (Very rarely, when the health a larva is seriously wrong, this character may lead us astray!)
Emmet (1985a), Davis (1987a), Seksyaeva (1990a).