Mag< The deer generally won't heat plants down to the ground. The love aeting buds and top growth but ain't into bending down to the bottom of the plants unless its winter and there's nuthin' else to eat..
Sounds like the work of Mr. Vole, a mouse sized rodent who uses the moles tunnels to get around. They love roots and the lower parts of the plant. They uswually will just eat that part and not the entire leafed out are. They can eat from under the ground or on ground surface and will kill yer plant if you dn't recoghize the damage early denuff to get it out of the ground and into yer plant hospital.
As fir killing the voles, mouse traps work best. Whereever you see mole activity (hills above the tunnels) who will probably see holes about 1 1/2 inch round. Thesew are vole holes. Set the trap with peanut butter as bait and be sure to put an empty flower pot over it so the cat doesn't home with a messed up paw, or yer nocternal critters don't ket their feet cuaghted either...
There are other products for voles and moles but chenicals and poisons which you don't really need to be using...
BTW, we have a dozen traps set and have been avaeraging 3 voles a day.