I've always find at least one oothecia in my backyard somewhere. You can always buy the egg cases from a garden center during early Spring and reintroduce them where you live. I haven't seen any grasshoppers around in a long time. Same with katydids.
Where the heck can you buy the oothecia? That is so cool, I will keep that in mind once this winter is through.
Lucky that you have them in your backyard, they are intelligent little buggers.