Lovely. The depth of focus is tiny at that distance, hey.
Regarding focus - lock it in at the magnification ballpark you want and move your body back and forth, instead of trying to hold steady and dial the focus in, the click away when needed. What I do for insects is move forwards until the eyes are in focus, then keep moving fwd until they just go out of focus, change direction and move slightly backwards and click.
Some tips I wrote a while ago when I was doing more macro:
http://piggo.com/2010/09/macro-photography-quick-tips/
http://piggo.com/2011/10/hunting-bugs/