Flower-Visiting Insects
of Rattlesnake
Hawkweed
Hieracium venosum (Rattlesnake Hawkweed)
(this plant isn't found in Illinois, although it occurs in Indiana; this observation is from Krombein et al; insect activity is unspecified; information is very limited)
Bees (short-tongued)
Andrenidae (Andreninae): Andrena krigiana