Spatial expression patterns of YRG at 15 h after head capsule slippage (HCS) during the fourth molt of 20E- treated specimens in Papilio xuthus. Black solid arrows indicate the position of 20E application, and the black dotted arrows indicate the position of 10% isopropanol application (control). Upper panel shows pigmentation pattern of a 20E-treated specimen. Dotted circles indicate the eye- spot region. Scale bar: 1 mm. (B) Spatial expression of BBP and YRG mRNA in P. xuthus, Papilio machaon and Papilio polytes larvae during the third molt. The pigmentation patterns of the fourth instar are shown left. Numbers in each panel indicate hours after HCS. Scale bars: 1mm. Arrowheads indicate yellow spot region of P. machaon and arrows indicate blue spot region of P. xuthus and P. polytes.