The monarch’s wingspan ranges from 8.
9–10.2 cm (3 –
4 in). The upper side of the wings is tawny-orange, the veins and margins are
black, and in the margins are two series of small white spots. The fore wings also have a few orange spots near the tip. The underside is similar, but the tip of the fore wing and hind wing are yellow-brown instead of tawny-orange and the white spots are larger.
The male has a
black patch of androconial scales on either hind wing (in some butterflies, these patches disperse pheromones, but are not known to do so in monarchs), and the black veins on its wing are narrower than the
female’s. The male is also slightly larger.
A color variation has been observed in
Australia,
New Zealand, Indonesia and the United States as early as the late 19th century. Named nivosus by lepidopterists, it is grayish-white in all areas of the wings that are normally orange. Generally, it is only about 1% or less of all monarchs, but has maintained populations as high as 10% on Oahu in Hawaii, possibly due to selective predation.
