I've only done a bit of research, but my understand was that while bats eat a lot of mosquitoes, they're so tiny that even a bat doesn't get much out of each on

I've only done a bit of research, but my understand was that while bats eat a lot of mosquitoes, they're so tiny that even a bat doesn't get much out of each one. The stomach contents of a tropical bat are less than 25% mosquitoes by mass after a night of feeding, IIRC. I admit I don't know if that's true of all species or in all locations.