Harlequin Bugs
 

I seem to have a bad infestation of Harlequin Bugs (and aphids too) on a
Kaffir Lime tree in my front garden - east brisbane, QLD. After hunting on
the net, the only real solutions I've found have been hand removal, or
spraying with detergent (as they're resistant to chemicals apparantly).
Does anyone have other suggestions for getting rid of them?
If I did use a detergent spray, what sort of mixing rate should I use (and
what type of detergent!)?
Thanks for any suggestions!