You got the eyes just about there which is one of the basics so you're in the right ballpark. But I'm guessing that as well as shooting with the lens wide open you were also using quite a high ISO as there's a bit of noise there. So that's two problems. A third is there's a lot of clutter. The latter, you can't really do a lot about as the bugs do what a bug's gotta do. To fix the high ISO, try to avoid shooting 'auto'. The 'P' mode gives you a little more control and you can set the ISO manually at 80 when light is good, and 200 when it's not so good, but try not to go above that as that's when the S5's pictures will start to suffer. For a little more control, and to avoid shooting at wide apertures use Av mode. Set the camera as small an aperture (higher F numbers are smaller) as you can while maintaining a reasonable shutter speed. You can work out what you can get away with by trial and error but I usually shoot close ups at F6.3 or higher.
Unfortunately you probably won't be able to use the flash with super macro mode because the lens obscures the flash when you get very close. If you get the macro bug, you may find the addon adapter and the Canon 500D close up lens to be worthwhile. This enables you to shoot at the telephoto end of the zoom from further away, so scaring the bugs less, and also means you can use the flashgun to help freeze the action.
HTH,
Eccles.