Fiction: White Millet is a cheap filler seed.
Fact: White Proso Millet is the number one choice of many ground-feeding birds like towhees, song sparrows, juncos, and buntings. The problem is that most commercial mixes contain more millet than anything else – a definite negative when put in a tubular or wooden feeder where perch feeding birds are looking for oil sunflower. If all a sunflower-loving bird finds in a feeder is millet, it will tire of kicking out the millet and move on, leaving you with a feeder full of uneaten seed.
A good mix will contain just enough millet for the ground feeders to benefit from the perch feeders’ habit of kicking out the seeds they don’t like, but not so much that the perch feeders will become discouraged. That way you attract a greater variety of wild birds both on and below the feeder. So, bottom line – a little millet is good, a lot of millet is bad.