Joel 2:9

They shall run to and fro in the city, being altogether unhindered in their advance; they shall run upon the wall, they shall climb up upon the houses; they shall enter in at the windows like a thief. Jerome writes concerning this phenomenon: "When the locusts come and fill the whole space between earth and sky, they fly in perfect order, as if obedient to a divine command, so that they look like the squares of a pavement. Each one holds its own place, not diverging from it even so much as by a finger's breadth. To these locusts nothing is impenetrable, fields, meadows, trees, cities, houses, even their most secret chambers. "