to be completely honest, I think the second and third pics would look nicer without the "bug". they'd then make nice macro shots of the flower.
For the bugs, try and get in closer, the bigger the bug is in the pic the better really.
and the last pic, I'm not sure where I should be looking. the spider is far too close to the edge of the frame, try getting it closer to the rule of thirds, also, getting a shot where you can see the legs and stuff.
other than that, they're nciely in focus, great colour, and nice quality, no grain or anything, very nice. it's not very visible in the first 3, but it looks like you may have some fringing going on. can be caused by the coating on the lens not being quite good enough, but decent lenses are ***** expensive.