Is the bee carnivore or herbivore?
Strangely, I would have to say bees are incidental carnivores. They don't intentionally hunt meat, but will eat the larvae and eggs if nothing else is available. Chimpanzees and Gorillas will catch and eat small animals if the opportunity arises for added protein. Humans actively hunt meat, so using this analogy, we could say the genetic "segue" of the bees, the wasps, got a taste for meat.
Of course with the hundreds of different species of bee, there would have to be one (there are three!)
that gets nutrition from meat.http://indianapublicmedia.org/amomentofscience/carnivorous-bees/
These aren't hunters either, but necrophages, scavangers. It seems they will also eat the live young and eggs from abandoned wasp nests and toad eggs.
I feel Ok with the source of food. I don't know what the bees may think about egg yolks. I would imagine if it was that bad for them they would reject it as tasting bad. Egg yolks are probably not the best thing for a herbivore, but there's no simple easy source of vitellogenin I can think of besides.http://en.wikipedia.org/wiki/Vitellogenin#Vitellogenin_and_honey_bees