Assuming you are talking about Japanese Beetles, there is nothing you can do to prevent them from eating your plants unless you spray everything with toxic chemicals or you spend a lot of time hand-picking them off. You can save your own lawn by treating your lawn with a GrubX type product or Milky Spore. But they beetles will still fly onto your property from your neighbors'. The traps attract the beetles to the area where the traps are. If you have a large enough property you can place the traps near your property line and try to catch some before they get to your gardens, but the traps only catch a small number. We have no grubs in our lawn and the beetles come from neighboring properties that are hundreds of feet (at least 300') from my gardens. From what I can tell, they will travel quite a distance for their favorite foods (which in my garden are hibiscus and roses).

I'm surprised to hear that you're finding grubs, since most of the scarab beetles that I see around here (Japanese, Oriental, and Asiatic garden beetles, among others) are now in their mature beetle phase, not in the grub stage. Any chance you were seeing something other than beetle grubs?

And, most types of grubs don't feed on everything, they have pretty narrowly focused appetites, with grass being their main food. That's why most chemical controls for the grub stage are used on lawns, not flower beds. So, I'd be a little surprised if they're the cause of these various problems.