Melanoplus spp.

Redlegged grasshopper on a leaf
Redlegged grasshopper on a leaf. Photo courtesy of Gilles Conthier. Licensed under CC BY 2.0.
Grasshoppers are general feeders which are occasionally a significant pest of field crops and are found throughout the world. They are most likely to be severe in drought years, when the lack of other food forces them into crops. Certain species of grasshoppers enter a swarm phase under the right conditions, forming massive swarms of millions of insects which consume anything in their past. Grasshoppers in this phase are referred to as locusts.
Grasshoppers are easily distinguished by their large back legs and their ability to jump. Adults grow up to 2" in length. Nymphs are similar in appearance but are smaller and lack wings.
Differential grasshopper on a leaf
Differential grasshopper on a leaf. Photo courtesy of Adam Sisson. Licensed under CC BY 3.0.
Grasshoppers feed on leaves. Damage is often most severe on the borders of the fields.
Insecticides are available for controlling grasshoppers. They often only invade the borders of a field, so the entire field may not require treatment. Always read and follow all label instructions.