Just read the posts after oat the bran thing. Sorry for the delay - after they eat the oat bran, they will bloat up, as the oat bran expands inside them. They crawl away and die - not exploding (I haven't seen any exploded bodies to speak of).
I guess I'm just a lazy and picky gardener - I don't have the time to crush the eggshells, I don't want to spend a fortune on commercial killers that may or may not work, and I don't want to waste a good beer! So the oat bran thing works for me - while I'm admiring all the nice
plants, I just sprinkle it around the beds.
I just put some down last week, ane then we got lots and lots of rain.
plants are all OK still - no holes in leaves. It not only works for hostas, but all
plants. Good luck.