That reminds me of a guy one one of the mailing lists I'm on. His neighbour dug a pond on his ground somewhere in a particularly mozzie-infested part of rural Texas. Plenty shade, trees around, nice big pond.

"But that's crazy", everyone said, "that'll be a breeding ground for more mosquitoes, that's where they'll all go!"

And you know what, they were right. It was hoaching with mozzies, who laid their eggs in the water, which then hatched into mosquito larvae.

Which were then promptly eaten by all the carp he'd stocked it with.

Year on year the circle of "not many mosquitoes any more" around his farm has expanded by about quarter of a mile.