I need advice from anyone who knows about pyrethrum sprays. I have put a large downpayment on a permanent yard spray system to get rid of mosquitoes. I am concerned about upsetting the ecosystem in my yard, however, as I am not sure just what, besides mosquitoes and biting gnats, this will kill. It is to be used at a .005 concentation, but will automatically spray 2 - 4 times a day. It this a good thing or bad?? Please help me decide....