Sorry, can't help you here. In natural areas around northeast Ilinois, two fo the most feared and tenacious and rampant introduced weeds are sweet clover (Melilotus) and loosestrife (Lythrum). Both are alwasy covered with honeybees, and natural areas manageers would do anything to get rid of the honeybees. I can't speak for the situation in New Zealand, but it is possible that the Ntional Park rules might prevent similar weed miseries. Keep informed..... Liz Day presently in New York City, USA receiving mail at [log in to unmask] (that's Lday, not ONEday) (formerly of the Chicago, Illinois, USA area)