Exodus 23:28-30

And I will send hornets before thee, which shall drive out the Hivite, the Canaanite, and the Hittite, from before thee. I will not drive them out from before thee in one year: lest the land become desolate, and the beast of the field multiply against thee. By little and little I will drive them out from before thee, until thou art fruitful, and possess the land.