Bumblebees and fuschia

While I was weeding I saw a hortorum worker enter a fushia flower.  She had to wriggle and squeeze herself to get in, and it was the high pitched buzz that attracted my attention.  Well she was in there for over a minute, and emerged covered in pollen, and went into the next flower.  Fuschias must be a good nectar source to take such a long time to deplete.  I'd never noticed bumblebees foraging on them before, but this one is right next to a cerinthe, which they love, so perhaps it was a lucky try.  I cannot imagine that a big fat terrestris would have any chance getting in, so perhaps it is just hortorum that can manage it.