Metamorphosis of the fruit fly Drosophila melanogaster is regulated by two hormones, ecdysone and juvenile hormone (JH). The developing eye and optic lobe (OL) present a unique challenge to this hormonal control because the eye forms progressively over a two day period and the resulting wave of photoreceptor ingrowth directs a corresponding wave of neural organization to the underlying OL. These waves of development occur during phasic pulses of both ecdysone and JH.