You could set out some snail traps and see what you catch, Carol. Alternatively, you could make a little collar around the base of your plants by using those cardboard sleeves they sell for coffee cups or some metal screen material if you have that handy.
I know snails and slugs have a huge appetite in GA now. I trap them by putting a small bowl or container close to ground level and fill with cheap beer. They will be attracted to the bowls of beer, climb in, and drown. I do not drink beer so I did not know that I used my hubby's "good beer" the first time I tried this. But, I did save my pansies.
I like the beer idea. At least they die happy. I brewed some strong tea and poured on my plants last night. Hopefully that will do the trick, if indeed it is snails that are munching on my plants. Seems odd that the little buggers would find there way into the greenhouse. I did see one in my lettuce that was in a pot on the floor of the greenhouse, so they may very well be the culprits. It sure is buggy here in GA!
Update: Its been a week and no more half eaten leaves. The tea worked, Yay!!!