Duckweed is a wonderful plant if you have vegetarian fishes like rainbows, silver dollars and some Rift Lake cichlids. Put as much as you like in the tank and the fish eat it.
All fish will eat damselfly and dragonfly larvae, the fish just has to be big enough to do it.
You can freeze the damselfly and dragonfly larvae with the mozzie larvae and feed it to all the fish later on. If the damselfly larvae are too big, cut them up with a pr of scissors.
You will continue to get damselfly and dragonfly larvae in the container of water with mozzie larvae. About the only way to stop it is to put a flyscreen over the container and have the holes big enough for mozzies, but too small for everything else to get through. And that is hard to do so just scoop each day and put them in a white bucket with some tap water. Look for anything unusual and remove or freeze it, and feed the mozzie larvae off. When you have too many mozzie larvae, freeze, freeze, freeze.