I have no doubt this will work. I've seen trout hit leader knots, split shot, strike indicators, etc. as well as a wide variety of items such as tree buds, small leaves, pieces of paper, cigarette butts....
At times we get so wrapped up in matching the hatch or figuring out the perfect fly for the day that we lose track of the fact that a hungry fish that is feeding actively strikes and spits out or sometimes swallows a wide range of items that are not "food". In your case the fish may be mistaking the knot for a midge or they may simply be striking something they think might be food.
Only thing I might caution guys who are thinking of giving this a try is to be aware of the regulations in your state/area in regard to the number of flies that can be fished at one time.