It’s hard to beat birds and bats for insect control. For example, purple martins and their relatives are excellent pest controllers, and they’re so used to living in human-supplied birdhouses that they often prefer them to natural nests.
Don’t hesitate to erect one or two purple martin houses if you’d like to keep your backyard free of pests, but don’t make the mistake of offering them feeders, or they won’t keep the insects down.
For round-the-clock pest control, provide bats with comfortable bat-houses to shelter in, and they’ll handle the bugs at night that the martins don’t get during the day. It won’t hurt to give the local toads a few damp places to hang out, too, so they can help with ground-level nocturnal insect control.