I was considering digging up a piece of a root, that grows naturally around these parts, near a ditch that the City doesn't always mow down,completely. Sometimes, they cut it & then no blooms & the Butterfly I guess would like to lay some eggs on those. But, the flower is much different than yours & may be incarnata, instead of coerulea ? I did notice, that bumble bees seem to be the :perfect pollinator, of them.
They even grew wild in Hawaii & I had a favorite, that was awesome & even better than the one called 'Incense' which I grew, just because it reminded me, so much, of the other..
I remember lifting on the 40' vine in the under growth to figure out, where it may have a flower, or hopefully locate a dryfruit even to get seeds, many years later, but no such luck !