VOLES! They destroyed about 50 lilies in a single year. Lilium Artistic and Longidragon. What did I do? Volblock/Permatil. Took care of the little buggers. I use Shotgun Deer and Rabbit Repellent and Milorganite to keep the rabbits at bay. My nemesis was a VERY large rabbit that I saw in the yard 2 winters ago, almost every day, and couldn't figure out why. Come spring I knew - 48 large tulip bulbs, all in one spot.
But he's gone, and I only have one small bunny. So I sprayed in spring until the buds got big enough (and the grass came in and became tender). I lost one bulb to frost and one to heat. That's all. Thank goodness!