I don't think the BTi would work well in Co., if you can't treat individual puddles or the different areas of standing water. A mixture of Perm-Up and Malathion sprayed on the mosquito resting places (do NOT spray anywhere near flowering plants - it will kill bees), sprayed every week or after every rain will keep them at bay pretty effectively.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).