Scribbly Gum

[John Smith]

I have recently planted a Scribbly Gum (Souther Sydney Area) and have
noticed that something is rather quickly eating away at the leaves...
(No, it not a Koala!....or rabbit!). I can't see any insects on or
around the young tree and most of the damage occurs at night. Does
anyone know what' eating my tree!? How can I stop it? Thanks in
advance...:-)