as queens last 2-3 years and many beekeepers replace the queen. This one was marked with yellow (I don't remember what year that means - I think there are five colors?). Basically the beekeeper grabs the queen with his/her fingers and drops a touch of paint on the thorax(?? the section between the long part with wings and the head) part of the bee body on its back.

I don't mark my queens. Worried I would accidentally injure them in the process.