I have a fish pond, and I see mosquitos larva but not many mosquitos, we usually have 3-5 green frogs working the joint and the goldfish and Koi do there thing. The water moving, but still I think its a net zero for mosquitos, as they are tough. Standing water by the woodpile will really hurt, but local bats also are very nice, but as we all know, the spring and all fall are all about natural balance transitions and when the temp of summer hits, usually things fall in line. Cheers.