Beetle time

Found this little critter roaming over the mandarin tree.
No idea what type of beetle it is, or whether it's a goodie or a baddie. Any suggestions/information gratefully accepted.
Don't want to get rid of it if it's a benign insect like a ladybird; but equally do want to if it's not. Nature's like that, and presents dilemmas like this all the time. 
Only way to know for sure is to do some online research, but what words do you use in a query to your favourite (non-Google) search engine? "Green beetles"? "Citrus beetles"? "Citrus pests"?
Think I got lucky with the query "Green beetles in South Australia", which brought up images of a bunch of green beetles (strangely enough) - including one with an uncanny resemblance to the one in today's photo.
I think we're looking at a Spined Citrus Bug, aka Biprorulus bibax, from , the Pentatomidae Family. 
Native to Australia, they apparently "make considerable damages on the fruits", and were classified as a pest in the 1980s. So I'm guessing this bug falls solidly on the baddie side of the register. Which is nice to know and all well and good, but how am I going to even find this guy again, let alone rid the lime tree of him and all his marauding family and colleagues?
More incisive research reveals you can control them by picking them off by hand and squashing them (mmm...), or by using an eco-friendly citrus spray, such as Pyrethrum. Heading to the garden section of the hardware store today.