[juneroses]

It's best not to add red dye to the mixture. There is controvery as to whether or not the dye harms the hummers; no conclusive evidence that I've read of but to be safe, omit it. Nectar in flowers is not red. The colorful feeder itself will attract the hummer.

The generally accepted ratio of water to table sugar is 4:1. For example, with 1 cup of water, use ¼ cup sugar. This most closely minics natural nectar. “Sweeter” formulas spoil faster.

It seems convenient to fill the feeder to the brim and forget about it until it's empty, but the sugary formula will quickly spoil in our heat. Better to put a lesser amount in, dump and clean the feeder 1-2 times per week, and then refill.

I've read that hummers won't eat the spoiled nectar (just as we humans won't eat a moldy sandwich). The “empty” feeder may be the result of evaporation.