The 'scribbles' on the bark of these trees are made by the larvae of tiny moths, which burrow under the bark. Like many eucalypts, Scribbly-gums shed their old bark each year, and when they do so the trails of the larvae can be seen as 'scribbles' on the new bark. The red gum (kino) is a response to damage, possibly caused by fire. I believe the fly is a Tachinid fly (Family Tachinidae), but I don't know which species.