It is one of the simplest of all flies. It should be weighted and fished dead drift near the bottom during spawning seasons. If you see spawning salmon, cast so the fly lands just behind them and drifts down stream from the spawning pair. Many fly anglers won't use an egg fly because it looks too much like bait. I think that is a silly reason not to use a fly.
Egg flies imitate a naturally-occurring food that wild trout, steelhead, and salmon eat with gusto.
These imitation Salmon Egg patterns can be found in any tackle store and are manufactured in a strange variety of colors and shades. The educated fly caster should realize that naturally salmon eggs are not bright colors. On the contrary they are generally of pastel shades of orange or red. Lighter colors will mimic nature more closely. This is why we only stock two natural colours.