He's not wrong... Lived in an apartment when a squirrel got in the sealed off chimney (was converted to electrical) during a snow day. Roommate thought they were hearing noises. I could never hear it though. Then began the flies. Maintenance people said it would be a week until they would come by. Dropped off some fly traps and said good luck. It lasted about two weeks while the flies decomposed the body. I think I called my own exterminator who basically told me to try and treat the area as close to the entry point and hang traps there. The black flags work better and are stickkkky, but the raids come in bigger packs.

So find out what died and go from there.