intersting bit of info I just found:

Another way to get hummingbirds' attention is to festoon (be tasteful, now!) your feeder with red or orange surveyor's tape, available in hardware stores. It is thought that hummers are sensitive to ultraviolet light, which these fluorescent tapes reflect in abundance.

Regardless, if you hang a feeder, sooner or later a hummingbird will come to investigate; it has been conjectured that, in a given year, not a square meter of the U.S. or southern Canada goes unchecked by hummers in their relentless quest for food.