Awesome. Any pics of the gnat carnage? As far as the cutting goes, as long as it isn't wilting, leave it in the water. Occasional wc will reduce the possibility of the stem rotting, but as long as it looks fresh and healthy, leave it in. Once it starts wilting, you know that it's not gonna put out roots. Otherwise, just let it do its thing. Some woody plants can take an inordinately long time to put out roots. Others would rather root in moist soil than in water. If the glass of water method doesn't work, experiment with your other cuttings in different methods. Rooting hormone is readily available at home depot (at least around here), and might be a good aid if you decide to try in soil rooting.