I caught my culprit red-handed.. or I should say green- mouthed. It is Deer. Caught him with it hanging right out of his lips.First the little plants went missing and I too thought it was a rabbit or a woodchuck. I thought they would get sick and stay away. ...Then the larger plants were ravaged. I did not think Deer ate Milkweed or even that they could but apparently they do. If you have deer in the area I would consider them my number one suspect!( iIf not keep a watch out and let us know who/what it is.)
I never had this problem in the past! Now all my natives are fenced in and my ornamentals are up for grabs.