Well done Charles. #2 came out well. Plenty in focus. I think they are hoppers of some sort, but as to which sort I'm afraid I have no idea.
#1 is a very difficult angle to get much in focus, even with f/25. Were you as close as you could get with this one? I'm wondering if you might have been slightly too close. Were you using manual focus or autofocus?
As with #1 I'm not quite sure about the sharpness of #3. Here too, did you get as close in as you could for this shot?
If you are going in very close (and are using manual focus), if you shoot from a bit further away you will lessen the chance of accidentally going in too close (where you can't get a fully sharp capture). Also, if you shoot from further out and then crop to get closer in on the subject you will have a greater depth of field than if you captured from close in and didn't crop.
I'm curious about the 1/60 sec shutter speed. You could use 1/250 sec with the D300. Sometimes, in bright conditions, a slower shutter speed can cause a loss of sharpness even though you are using flash. This is especially the case as you are using a relatively high ISO of 800.