Deb,
My experience is only with dried mealworms and bluebirds. I find that the bluebirds ignore them unless they are feeding their babies, which usually begins around July 1. While they are feeding the babies, they go through a LOT of mealworms, some days I have to fill the feeder a couple of times. lSince you are in Minnesota, you should have some bluebirds around! If you have an open dish feeder, try setting some out the beginning of July and see what happens!
With robins, they won't come to the normal hanging feeders, robins are either high in trees, or they forage on the ground. So I would try a dish of the worms on the ground where you normally see the robins. It may take a day or two for them to find the worms. Also, I haven't paid attention to when the robin babies are around, but I would think they are earlier than bluebirds.
Alyssa
