Dont edit out the vise...it gives your photos a wonderful context.
You might consider shutting the aperture down a bit and and bumping up the light. Doing so will extend your depth of field and allow all of the fly to come in focus.
Although great portrait painters of old had their subjects illuminated with a single source of light in order to "anchor" them, and a photographer is well advised to do the same, it might be appealing to at least highlight the opposite side of your flies by using a simple reflector made of foil. If for no other reason doing so might bring out a few more details by lifting the shadows.
Dont forget that when you illuminate from the side (at a shallow angle) textures are enhanced, which, is helpful. A single light source is perfect in this regard.
Finally, the closer a light source is to the subject, the softer (less contrast) the light. The further a light is from the subject the harsher (more contrast) the light. Either can be beneficial per your intent, however, I would suggest a softer light at a shallow side angle as most desirable. But then again, thats just me.

"Anticipation beckons us to the turmoil of the stream; the fruits of our labor and device realized in the rippled take." ~ Michael T. Shuey