I agree about the base looking like it is almost touching the stones.
This is probably because you have no DOF. And so everything is in focus, so it looks like the objects are all together.
If you add a little DOF it will give the scene volume.
You could move the bug by the zapper away to a darker area, and then use post-processing to add the electrical zap, giving you more control over it.
I hope you don't mind, but I copied your picture and added some post-process gaussian blur to get the image below. This is not exactly what you would get with DOF, but is similar.
http://img.photobucket.com/albums/v4...ithwalkway.jpg
Doing this also makes the front bug the focus of attention.
I'm not sure if DOF would work for you, but as the scene has a lot of depth, I would certainly give it a try.
~~CM!