Flyways - Papilio canadensis

Here is an example of a "flyway". Basically it's just a open corridor lined with trees. The best ones for finding tiger swallowtails (at least Papilio canadensis) are old 4-wheeler trails, fire roads etc. that are surrounded by early to mid succession forest. Here is an example of one of my very productive flyways along a cottage road that is surrounded by forest:

In my experience good flyways are trails lined with:

1) The primary host plant (e.g. Trembling Aspen)

2) Good nectar sources - flowering bushes with broad leaves seem to be frequented most.

Here is a flowering bush I caught 2 females fluttering around this summer:

Please suggest IDs of the above species if you recognize it.