Interesting about the bees on the salvia--
Ann, where did you pull that from?
Any idea what kind of bees they are?
Carpenter bees are known to bore through the side of flowers with a deep tubular corolla to get the nectar. Usually then other insects will use the same holes.
I have read about honey bees and some other bumblebees following suit, but I have never seen that--I figure it's too much work and when there are so many open flowers around they don't need to bother.
I have seen the honey bees come at the back side of open flowers, like this geranium, fairly often. They stick their tongue in between the petals, at the base. It's like they are checking the nectar flow and if it's good they will come around the front side for a thorough trip around the base.
If you look at this pic
you can see where she is putting her tongue--they go around the base nectaring that way. The pollen is up on the anthers and rubs off onto the bee.
With the salvia, the nectary is also in the base of the corolla. Very neato lever action method of pollination--as the pollinator pushes in to get the nectar the stamens move to deposit the pollen onto the pollinator, who then carries it to another hopefully receptive flower (stigma). Amistad is a hybrid with a very deep corolla and my guess is that SCButtercup either has carpenter bees or carpenter bee wannabees trying to cheat that mechanism.