Different processes that lead to the development of halteres instead of wings by Ubx. Halteres and haltere discs are in red, whereas wings and wing discs are in blue. (a) At the end of the embryonic development, Ubx activity makes the haltere disc about half the size of the wing disc. (b) During larval development, Ubx regulates many signaling pathways to determine haltere disc size and to specify haltere development. (c) During pupation, Ubx reduces cell size in the haltere disc as compared to that of the wing disc and also determines cell differentiation. The final result is the development of a haltere instead of a wing (d).
