Wow , yours are much better. I'm just starting out in this hobby. Did you use auto focus on those pictures? I've only been using legacy glass and manual focus. I do have the 18/55 but have only tried it once. The pics you have taken seem much more crisp. Thanks for sharing.
I don't think they are any better than yours. I think yours are great. I love that shot you got of the one flying away and the last one too.
I use the auto-focus to get me close then manually focus on magnified view to try and get the damn bee in focus before it buggers off. I'm generally flaying away here and no idea what I'm doing but some shots come out nicely.
I think a difference in our shots is that the flowers my bees were on were a little away from the background grasses and other plants making the bee and flower more isolated and your yellow bee and yellow flowers don't stand out as much the red bee with the uhh (man alert! Don't know colours) purplish flowers.
I've only used SEL lenses so far (I'm just starting out too) so I'm not sure how much the OSS is a factor. I really want to give manual lenses a go but I'm waiting until the beginning of the year when I return home (I'm an expat) for a visit to scrounge through my father's old Nikkor and Vivitar lenses and see what he had.