I know the work of:
Lawrence E. Gilbert: Pollen Feeding and Reproductive Biology of Heliconius Butterflies. Proc. Nat. Acad. Sci. USA, 69(6): 1403-1407, 1972,
I also know, that Micropterigidae feed on pollen, but this is not my interest. I am interested in feeding of butterflies with a proboscis.
Thank you very much for your answers!