We've seen a hummingbird eat from the feeder.

I kept overripe and rotting bananas and other fruit in it from spring through frost last year, and never once saw a hummingbird paying attention to it. I'll try again this year, but don't have high hopes.

This product works great, just give it a couple of weeks. I put it with 2 other feeders of nectar, after a week or so they started eating the protein! Love it!

I received a hummingbird protein feeder 8/22/17. I put some old bananas in it right away.  Some of the bananas already had fruit flies on them.  After about a week I saw the first hummer visit the feeder. 8/28/17, I was filling the ant motes on the tops of our nectar feeders when I saw a praying mantis catching fruit flies in the protein feeder. The mantis stayed on the feeder for about two hours just picking off the fruit flies. 8/29/17, I saw and photographed a robber fly catch and start eating a green fly, that was visiting the protein feeder. I think these would be great for children, so I bought one for my granddaughter. Besides seeing the hummingbirds attracted to the protein feeders they can also see fruit flies and other flies, and the predator insects that feed on them.

I only have about 6 Hummers which are using it. I tied up the top and use it for butterflies and native bees. They flock to rotting fruit. Best for mine have been bananas, cantaloupe perl and seeds inside and oranges. They all use it and love it.