Spring Bird Food

It's become apparent to me that if I want to keep attracting birds to my feeders in spring that I need to add some natural food, like worms, etc. It has been pretty dead at my feeders, other than the occasional Blue Jay, House Finch, Chickadee, Titmouse, and the annoying Mourning Doves. But there are just a lack of birds, in general, because of birds going off and claiming their own territory, where winter is pretty much nonterritorial and there are many more birds eating seeds since there are no insects, etc. to eat.