We spray the coop once a year and hubby did it last weekend, but didn't spray the 6 week old chicks. They are going crazy today with the knats all over them. I know they have to be sprayed or they will die. I hate them buffalo knats. I called the Farm Supply and they told me to spray a fine most over them, being sure tot ake up their water supply first so it doesn't get contaminated. One of the ckicks died lastnight and he said it looked wet thin morning. not sure what would cause that, but I suspect the knats got it.