The milkweeds sure do attract visitors.  Pleased to discover a very small stand of swamp milkweed (Asclepias incarnata) in an easily accessible area, I decided to stay awhile to see who came by. Here are some of the insects I saw on it.

This is a pearl crescent butterfly, Phyciodes tharos, a member of the brushfoot family (Nymphalidae).  

See the blurry orange thing in the foreground?

That’s an assassin bug (species unknown, family Reduviidae). They sometimes hide in flowers, but more often actively hunt their prey*.  They use their rostrums to inject prey with salvia, which then liquefies the victim’s insides so that the bug can suck them out.

I have a sudden, strange urge to watch Starship Troopers again.

In less gruesome news, the milkweeds were also attracting the bees.

I have no way to identify the species of this bumblebee (family Bombidae).

[edited to add: see comments]

*Encyclopedia of Life