Those little yellow flowers can be purchased. We had hummers for a few weeks. Then disappeared, and now are back. Because of the heat and quick mold growth, I change the syrup every other day. More than that, and mold appears. I use 1/4 c. Sugar to 1 c. Water. I let it boil a short while to help it thicken just a tad. These little birds are so fast that it's difficult sometimes to see them unless you're stationed close by. As others said, keep the feeders clean and filled. They also seem to have a flight plan! Good luck!