Last August I was watching this little native bee through the lens. She was hanging onto a thistle with her two front legs while she scraped pollen from her body with the middle two. Then the middle legs passed the pollen back to the rear legs which packed the pollen onto her abdominal scopa. Very coordinated.
She was deep in a thistle, tail in the air minding her own business, when a yellow-faced bumble bee alighted on the same flower about two cm away. The other forty or so flowers were empty, but of course the bumble wanted the one already occupied.
Although there was plenty of room for both, the bumble sidled up to the little bee until they were side-by-side, then the bumble lifted one foreleg and kaboom, struck the little bee in the face and gave her a push.
The little bee lost her footing, fell from the flower and flew away. The big, fat bumble—all alone now—foraged on her prize for a few seconds and then left. Having won the battle, she was no longer interested in the reward. Below is the attack sequence.