I don't remember when cilantro is at its growth stage here. But if it will repel grasshoppers I'll try to plant a lot of it in places. When I first tried growing it I use to get bad headaches when I went to that part of the yarden. It took a couple years or more to figure out what was causing the headaches. I don't think it bothered me the last time I grew it.
Chickens and ducks are great 'repellers' of grasshoppers, etc. I really don't want to just repel them, I want them DEAD!! There is a disease spore that kills the first generation which the second generation eats ingesting the disease and having a worse case of it, ad infinium until the population is mostly if not totally killed off in some areas. The trick is to sow it at just the right time and in the right place. It is harmless to anything else. It's available thru most seed catalogs. But then I would miss the fun of watching my banties and ducks chase, catch and eat them.
GOD bless and keep each of you.