We have a lot of swallows (mostly barn and green) on our rural property. Wife is currently battling a pair that wants to build a nest above the back door. Anyway... In the evenings and mornings there might be one dozen or more contstantly flying around between our trees eating insects. Somewhat mesmerizing to watch. Gemini says a single swallow eats about 850 insects per day. Pretty sure that includes a high percentage of mozzies and flies. 850 x 12 = 10,200. Let's assume 50% mozzies (we have lots). So 5,100 fewer per day. Go swallows Go.
Reminds me of a story I read about an overpass in Texas that housed tons of bats. It creeped some folks out, so they disallowed them to roost. Once the bats were gone, the neighborhood was overrun with insects. Did not take long to have the humans get the bats back. Go bats go.
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.