As you can see they're rather pretty little patterned flies, even if they are evil wee blighters. As V. G. Dethier says of another fly in his or her wonderfully eccentric book The Hungry Fly:
"If we are able to overlook the fly's scatological way of life, we see a thing of beauty, a jet jewel (.....) whose diaphanous wings bear it aloft with consummate skill, the curvature of whose eyes flows in smoothest arc, whose faceted design rivals the honeycomb in hexagonal perfection, whose hairs curve in marvelously fluted columns rivaling the best in Gothic architecture. And privately within, its softer self is laced with the exquisite silver filigree of its air-filled tracheae. There is perfection in its parts and gracefulness in all its movements."As for what she's laying eggs on, use your imaginations people.