I have seen a lot of insect species at this particular plant. As one might expect, there are bees. The bees above are both sweat bees in family Halictidae. The one on the left looks like an Agapostemon sp. (possibly A. virescens). The one on the right looks like something from the tribe Augochlorini. None of my photos of it are clear enough to move it beyond that.
I have also seen mosquitos landing on the flowers. In their case, I'm not sure if they are nectaring or if they are simply resting while they wait for the next warm-blooded creature to walk past.
The flowers are also visited by butterflies. So far I have mainly seen Cabbage Whites flying around them. This one visited the flowers long enough for a few photos. True to character, it kept shifting its position, but this one stayed in the same part of the bush for a few minutes.
It was disturbed whenever other insects wanted to get in on the action – in this case, a Common Eastern Bumble Bee.