Two Bumblebees Working a marigold

These two bumblebees were working the same flower. One is huge and the other is quite small in comparison.....same species, but different sub-species. First I thought the large one was trying to suck the liquids from the other bumblebee, but no after gently spreading them apart, I noted that they both have their probiscuses deep down deep into the center of the flower. They are definitely are preparing for winter.