Exodus 23:28-30

I will send the hornet in front of you, and it will drive the Hivites, Canaanites, and Hittites away from you. I will not drive them out ahead of you in a single year; otherwise, the land would become desolate, and wild animals would multiply against you. I will drive them out little by little ahead of you until you have become numerous and take possession of the land.