There were many factors that affected people who lived in the Great Plains during the Dust Bowl era. What was the main factor that drove people from the Great Plains?

The Dust Bowl was caused by several economic and agricultural factors, including federal land policies, changes in regional weather, farm economics and other cultural factors. After the Civil War, a series of federal land acts coaxed pioneers westward by incentivizing farming in the Great Plains.

Explanation:

1) Manifest Destiny: The US Government wanted settlers to move onto the Plains as they needed the land to be settled and farmed and for communities and towns to grow up and expand. This was needed if the USA was to be a rich and successful country. The government therefore promoted the idea of Manifest Destiny.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.