Flower-Visiting Insects
of Water Smartweed

Persicaria amphibia (Water Smartweed)
(Bee activity is unspecified, while the wasp sucks nectar. Robertson's observation could be referring to Persicaria coccinea, which was considered a variety of Water Smartweed in some older taxonomies. Observations are from Robertson and Steury et al.)

Bees (long-tongued)
Apidae (Bombini): Bombus perplexus (SDO)

Vespidae: Vespula germanica sn (Rb)