Haplorhynchites aeneus - Head-clipping Weevil

My niece emailed me about seeing here cone flowers with their heads cut, thinks it is female head- clipping Weevils doing this. She lives on Vancouver Island BC. Checking out this head - clipping Weevil and not sure how they get into your garden. I have a lot of Cone Flowers in my garden. That would be disastrous for me. How do they get into your garden and how do you get ride of them is my question.