If it came in four to five years ago as a noxious weed or something, well, if they wiped it out, fair enough. But it was here as the basis of my existence. The goal of the insect is not to eradicate their host - they just want to live and survive on it. So the idea with biological control is to bring the plant to a level where it is not a problem - to the point where a farmer doesn't have to go out and spend dollars on chemicals to control it. The crown weevil attacks the crown or base of the weed.
Adults eat the rosette leaves and then the female lay eggs in the rosettes and leaf stalks.
When the larvae hatch they feed within the stalk and mine down towards the crown and the tap root. Ten to 20 mature larvae can kill an average rosette. Trials at Yanco near Leeton in New South Wales show the insects multiply quickly, jumping from 60,000 to 150,000 in one year. Paterson's curse crown weevils have been given out to farmers around the country. Some are happy about the insects.