Those hostas and other perennials that are just emerging for their new season are taste treats for deer, rabbits, and other herbivores. Your best bet to protect your investment in those plants is to make them taste terrible. There are several commercially available preparations (Bobbex and Liquid Fence are two examples) that consist of putrefied eggs, mint oil, garlic, and other ingredients that deer and rabbits find noxious. These preparations are applied using a home sprayer. A spraying of all new foliage is best when no rain is in the immediate forecast. For an hour or two, your yard will smell terrible. Once the sprays dry, humans no longer detect them but deer and rabbits avoid treated plants for up to a month.