hot pepper/garlic spray will make them a bit less palatible to leafe eaters. But to rid, iradicate them totally, takes some pretty toxic chemicals, I believe.
When i have that problem outside.. I make it a twice a day ritual to search out grasshoppers, and rip their little heads off. I like killing them bastards. Except the place i used to guerilla grow- there was some tiny little pshchedelic ones, and it was a natural preserve area. So i left them alone or relocated them away from the plants. I had a leafhopper or catydid that was shredding my thai male, I finally got him yesterday... Fed him to my cats!