mamajack,
Can't recall any butterflies using goat's rue (galega officinalis) as a larval host. It is not from the rutaceae family so the BST won't use it. Looks pretty blooming though. Considering it is from the fabaceae family - it might be used by some skippers, blues or hairstreaks though - I've never seen a plant - then again, never knew about them until googled it!!!
Was reading about the goat's rue - interesting - how metformin was discovered - and also how it has a sedative effect on fish. Which is funny when I think of the two unrelated remarks - because metformin reeks of a fishy smell!!! ROFL!!!
~ Cat