I just commented on another post here about bunnies eating their little way through the garden. A baby bunny is tiny and can get in and eat a whole head of lettuce easily. I can't grow lettuce mostly because of that!

Melissa, do you think bunnies would browse and eat a leaf here and there or it would chomp down an entire mature head of lettuce overnight?

I suspect it is either a bunny, rat, or a groundhog. I always had marks on my tomatoes but never before had an entire head of lettuce cleanly disappear.

Was the lettuce pulled out or cut? How much is left? I'd suspect your human neighbors first.

Seems like the root is missing as well. If my human neighbor did it, why wouldn't he/she take more than one?

Guilt.

I honestly don't think that sounds at all like the pattern animals follow. Animals DO move around as they feed, and would most likely damage multiple plants in the process. And, they do leave stubs/stalks behind.

To me, it sounds like someone wanted a head of lettuce. Why would they take just one? Because that was all they needed at the time. Perhaps they'll be back to take more later. You can hope not.

Perhaps you could try something to discourage theft. One idea that might work, the fake-out -- dust the plants with some white flour or corn starch, which of course would be totally harmless, then put up a little sign that says "Danger, Poison -- these plants have been treated with insecticide. Do not touch. Do not harvest or consume these plants for 14 days, until May 24, 2012. After harvest, wash thoroughly" or whatever.

Oh I love that fake out idea, so amazingly sneaky!! lol

Ooh that fake out idea is brilliant!! I already did some rabbit/rodent spray around the perimeter of the lettuces but I may try that white powder idea.