As the leaves unfurl in spring, there is a brown indented ridge mid leaf that eventually breaks the leaf and if falls off. It looks like an animal chewing but it isn't. It is not slugs.
Empress WU Hosta
Certified GKH Gardening Expert
Is this the phenomenon you are seeing on your hosta: http://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/images/Pests/Hosta_Leaf_Nematode20.jpg
If so, it is the handiwork of nematodes. For more information on nematodes, please visit the following link:
For more information on the care of hostas, please visit the following link: