Red dye is totally unnecessary to attract hummingbirds. The feeders have the color red on them and that attracts the hummingbirds. Red dye #40 is made from coal tar and has been reported to cause tumors on the bills and liver of hummingbirds. The purchased nectar also contains preservatives that can harm the birds.
A simple receipe for your hummingbird feeder. Mix 1/2 cup of sugar with 2 cups of water. Put in a sauce pan and warm it until the sugar dissolves. Put in feeder when it cools. Change once a week or more often if you see mold forming.