Revelation 9:3

Locusts came down. Compare Joel 1:7-12. Locusts look like a giant grasshopper. A swarm of locusts drops down out of the sky, like smoke, darkening the sun-light, falling on the farmer's fields and quickly stripping every leaf off the growing plants. Locusts, then, symbolize destruction, grief, hopelessness, despair. Locusts are just the right symbol for John to use to describe the forces of evil which pour out from the abyss, bringing horror and destruction. This kind of locust does not harm the grass, or trees, or any plant. They can only harm those who do not have God's seal. God's people are sealed (Revelation 7:1-8), and have the promise: "he will not allow you to be tempted beyond your power to resist" (1 Corinthians 10:13).