Scribbly trees

Tangential to my research on the writing/drawing continuum is a scribble that occurs in nature - under the bark of some 20 species of eucalyptus trees, mainly on the east coast of Australia. It's made by the larvae of Ogmograptis scribula. There are half a dozen species, and at least five distinct scribble patterns.

Scribbles are caused by moth larvae feeding on photosynthetic tissue just below the epidermal cells in the tree trunk.

Pix from here and here.