Who or What is a Ratbag?

Returning from a fantastic week on Lord Howe Island, it was a no-brainer to cover rats on last week's radio spot.  A debate is raging on the island about the planned eradication of rats in 2010 and local artist Ginny Retmock had produced some 'ratbags' for the community market.  I bought a few for giveaways but hadn't thought much about the term 'ratbag'.

Presenter Andrea Close asked listeners about the origin of the term, and we decided listener Joyce was probably right in saying it was associated with wanting to keep away from rat catchers who carried a 'rat bag'.  However, a bit of searching since reveals the origin might not be that clear cut.  Most web dictionaries indicate the term as a common Australian one for a larikin; a non-offensive term for someone.  But in use in other parts of the world it seems the term can be for nosey older women or for causing damage ("I got drunk and ratbagged the place").  I couldn't find any historical reference for the term originating from the plague or rat catchers or the like.

Don't let me give the impression Lord Howe is overrun with rats.  They are problem for biodiversity, the kentia palm industry and some locals, but tourists would normally not know they were there.  It's just my particular interest...