High Quality Content by WIKIPEDIA articles! The Regal Fritillary (Speyeria idalia) is a striking nymphalid butterfly found among some of the remaining tallgrass and mixed-grass prairies in the east-central United States. This prairie-specialist butterfly has a characteristic deep orange color and unmistakable dark hindwings with two bands of spots (Brock 2003). On the female, both bands of spots are white. However, on the male, the outer band of spots is orange in color. Females also tend to be slightly larger than males. The ventral surface of the hindwings is olive brown to black in color with bold silvery white spots (Selby 2007). The wingspan of S. idalia usually measures 68–105 millimetres (2.7–4.1 in) (Selby 2007). Flight is in the summertime from approximately June to September and adults tend to be swift in flight, coasting close to the ground (Brock 2003).