Arrangement of Scent Scales in the Male Wings of the Small White Cabbage Butterfly (Lepidoptera : Pieridae)

In the genus Pieris (Lepidoptera : Pieridae), scent scales are widely distributed in the male wings. We made a detailed study of the scent scale arrangement in the wings of the small white cabbage butterfly, Pieris rapae, by examining sockets, which are small attachment points of scales. Scent scales form rows between those of the ordinary scales in the anteroposterior direction of the wings. Most scent scales are evenly distributed within the rows, but some are separated by much larger intervals. The density of the scent scales is about 180 scales per mm^2 in the forewing, and about 130 per mm^2 in the hindwing. Its ratio to that of the ordinary scales is about 0.4 in the forewing, and about 0.3 in the hindwing. The ratio in the part where scent scales are evenly distributed within the rows is about 0.5 both in the forewing and in the hindwing. The distribution region of scent scales in the whole wing is definitely outlined. These results provide bases for studies of differentiation and arrangement development of scent scales in the pupal wing epidermis.