Surprisingly, we don't have a problem with mosquitos not sure if the bats in the evening hours or maybe frogs eat them not sure why but you won't hear me complain. We don't feed the fish in the pond so maybe they eat them as well.
Have you asked neighbors for ideas? I have sometimes had good luck doing this over the years since they know the usual problems and solutions in the local area. There’s an app online called “next door” that is local. That might help too. Good luck!