The Mom regurgitates nectar and partially digested insects into the babies' open mouths. Yummy, eh?

Thanks ctnchpr,
Do hummers eat alot of insects, or is it mostly nectar they're after?

They feed on very small insects and spiders, finding them on plants, tree trunks, and even on the outside of windows. They also feed on protein rich pollen. They will take advantage of sapsucker holes, too.

Thanks rhizo.