Insteasd of Cosmopholites sordidus, I think this is a serious pest of lawn grass accidentally introduced into HK. I hope it is not firmly established yet. The weevil is originated from the US. I have compared 亞豬 's photo with my picture. If you found that they were the same, then the species would be Sphenophorus venatus.
It is worth telling the 'manager' of the spot when you spotted the weevil so that appropriate treatment should be carried out.