The formula for the feeders is 4:1. In other words if you use four cups boiling water use one cup of sugar. Stir until dissolved. Let cool, fill feeders, store leftovers in fridge. Do not use honey as it promoted bacterial growth and causes other problems for the hummers.
Do not let this solition set in the feeders for longer than three days as molds and bacteria build up and can kill the little hummers. The feeders should be emptied, washed with soap and HOT water, rinsed, and refilled for another three days of feeding if it lasts that long.
We have seen only about four hummers this year. Have not had the humming, buzzing, dive-bombing as usual.
I too leave food out until about Sept. for the stragglers.
My neighbor usually has 50 to a hundred she feeds but this year she is at her other home in Delaware. Can't imagine why then thay aren't more prolific here at my place since I am feeding them. Oh well, there is lots of summer left.