"Though I haven't tried it in the greenhouses I have had good control at my house with cornmeal. Sprinkle some in the areas they frequent. They carry it back to the nest. Appearently cornmeal cannot be digested by ants so it wipes out the…"
Jerry Montgomery has some good advice, I may add that you should also include cost for depreciation, marketing, and development. In other words you someday will have to pay for new plastic or glass on your greenhouse, or water pipes may need…"