If you have over wintered any plants in pots such as fucshias in particular, just knock them out of the pots, pull the soil away from the roots and you will easily see the grub. Kill them all and repot the plant in fresh soil and treat all your baskets and tubs in late march when you have planted them up.
I grow about 100 fuchsia cuttings and almost the same in geraniums and didn't get a single grub last year.
I will definitely be buying them again this spring.