You should fill hummingbird feeders hung during April to 1/3 capacity since many birds have not yet reached Michigan. In May you can fill the feeders halfway. Although hummingbirds leave Michigan in late August or early September, you may wish to leave feeders 1/3 full for two weeks after the last sighting to feed any late-leavers.
Never fill hummingbird feeders to capacity because you need to be empty and clean them every three to four days when exposed to Michigan's summer heat. Black spots on the inside of a hummingbird feeder are usually mold and you'll need to be scrub them out.
In addition to bright red hummingbird feeders, several flowers and bushes attract hummingbirds. Flowers include fuchsias, impatiens, petunias, geraniums and begonias. Butterfly bushes and honeysuckle are among hummingbirds' favorite bushes.