Second, the extra people you employ, aside from the obvious mind-numbing drudgery and hard labour you're ruining their lives with, would have a carbon cost.
Third, I can see that some pest-control chemicals are bad for the environment. However, it seems also clear that the demarcation line between eco and non-eco is not the same as the line between organic, and non-organic. In fact, it seems like there is no relation at all. There are many chemical pesticides that are not environmentally damaging, and many traditional farming techniques are environmentally damaging.