Question

what is the good that grasshopper eats

Answer 1

Corn, wheat, barley and alfalfa

Answer 2

Fresh wheat leaves, corn leaves and other vegetable plants may also be eaten. But actually, many plant species will be eaten by grasshoppers. You can try to feed them any kind of grass-like species; if they eat the plants, it means that this is a suitable plant species.
hope will help you serhan ; )