If it's on your patio, it's in a pot, right?
If you have some chicken wire and don't mind "ugly", you could make a cage to rule out critters. "Buds" sound like deer or some other critter that has so much to eat that it only takes its favorite foods.
I don't think slugs can swim, so you might set the pot into a plastic bag (so it doesn't flood from the bottom up), then set the pot and bag into a large, shallow saucer or tray. Flood the tray deep enough to drown a slug. 3/4"? 1"?
Or just park some beer saucers around the patio - if you can trap some, they are probably eating something!
If it can get past both saucer and chicken wire, it either swims or flies (or hides in the soil of the pot).
Maybe some sticky paper like flytrap paper? More as a way to ID the culprit, than hoping to depopulate the whole neighborhood.
