Exodus 10:2

See on Exodus 7:4;

3. This question shows that Pharaoh was responsible for the hardening of his heart: see on Exodus 4:21.

4-6. Travellers are unanimous in bearing witness to the terrible ravages caused by a visitation of locusts. They fly in dense swarms, sometimes miles in length, so that the air is darkened with them. Wherever they alight they devour every green thing, not sparing the bark of trees. For a description of a locust plague see Joel 1:1; Joel 2:1, where the locusts are compared to an army of horsemen.