This little weevil was on the Garlic Mustard in the garden when I came home. I think a combination of a slow approach and cold weather meant that I did not scare it off and I was able to watch it drilling into the flower buds.
This is the main purpose of the weevil beak, the rostrum, seems to be to lay eggs inside plants. This to me is what makes weevils weevils and sets them apart from the leaf beetles: whereas leaf beetle larvae feed on the outside of the plant, weevil larvae feed and develop on the inside, although there are many exceptions to this (notably the broad-nose weevils and the bark beetles). I thought this weevil, Ceutorhynchus pallidatcylus, might have been laying its eggs, but it is supposed to do this in the leaf stalks, not in the flower buds.
After drilling down in withdrew its rostrum.
I did not see what happened next but it plunged its beak back in again, perhaps to push down an egg, perhaps to feed on the developing parts of the flower. I do not know what it was doing, but I do know that a weevil beak is an effective drilling tool because last year when I was handing a Curculio glandium it got annoyed enough to start drilling into me!