This usually happens when using TexturePacks. Most likely corrupted texturepack file. Might want to try to redownload it, or report it to the texturepoack maker
I have traced the issue to the following: load any texture pack at runtime (that includes server texture packs), and it'll corrupt the bees. Even if you unload all texture packs in the same minecraft session (ie: switch to a different single player world after disabling the packs), it will still be corrupted. Only a complete reload will fix it, until you load a pack after booting up minecraft.
So my solution was simple: no more server texture pack and distribute the textures to everyone so they can load it at startup instead.