Some Darwinists have suggested that ancestral four-winged fruit flies could have evolved by mutation into modern two-winged fruit flies. But this explanation doesn’t work, because a two-winged fly hasn’t simply lost a pair of wings; it has acquired a large and complex gene (ultrabithorax) that enables it to develop “halteres,” or balancers. The halteres are located behind the fly’s normal pair of wings and vibrate rapidly to stabilize the insect in flight. So the two-winged fly represents the gain—not loss—of an important structure. (See Chapter 9 of my book "Icons of Evolution"). (Emphasis mine)Really?
Well, Jonathan Wells, tell me, why is this large and complex gene found in other insects than Diptera?