I recently went on a bug hunt on the vaal, looking for a few subjects for my new Macro lens. I was absolutely shocked with the sheer volume of aquatic insects that you would pick up with every sweep (I used a thin gauze colander).  I also wanted to inspect some of these guys under the UV lamp to see if there was anything to my hunch on UVs effectiveness on caddis and worm nymphs, and seemingly less effectiveness on mayfly nymphs and perdigons.

I couldnt quite get a focused shot of the caddis while trying to hold camera, uv lamp and get my nymphs to behave, but they also have serious flourescence under their heads and on the underside of the tail. The mayfly nymphs I found seemed to contain no bioluminescence. By volume, it was mainly mayfly nymphs, and I did witness a spectacular mayfly hatch in the early afternoon, with thousands of flies emerging from the surface.