Good hygiene, diligence and observation plus treatment for control of vne weevils. Where you can.....e.g. Heucheras, primulas, fuschias, etc.. Wash soil from roots. Then 2 treatments are possible - chemicals or nematodes. Chemicals like Provado can kill almost all the larvae. Nematodes control the numbers but will always allow others to survive. You can't use nematodes and chemicals together but I use a mixture of all treatments to control vine weevils. Night time catching vine weevil adults helps too