The color black is used very successfully in many fly patterns whether in the body material such as silk and rayon floss, threads, and hackle, both cock and soft hackle. These are used in the pattern singly or in multiples to create flies from ants to streamer flies. I'm sure most of you are familiar with the woolly bugger, especially the black version and know of it's prowess to take fish. One of the problems with black is the anglers ability to see the fly on the water. Some patterns have incorporated hot spots of color such as orange, or white. These work but I prefer to just float the fly and see the rise. Here are a few black flies I have tied and tried. They work and should have a place in the anglers box.
A standard upright hackle black fly. Can be a representative of many land based insects.
This little guy could be a beetle, and is tied with cock hackle palmered, and a black soft hackle collar. Deadly at times.