I feed mine dry so avoid this problem but in the heat I have been serving up a sachet in the evening either with crushed ice or extra water in it, or cat milk. it also gets demolished. Applaws definitely has this effect.
One of my cats only likes dried food so that is fine, the flies don't seem interested in that.
The fussy old cat gets a mixture of pouches & dried food, so I just give him as much of the pouch as I think he'll eat at one sitting then a bit more if he's still hungry. Then I leave out some dried food for him to graze on.
The dogs are more than happy to wolf down any leftovers. I think they like it better than dog food!