Its wings feature an easily recognizable orange and black pattern, with a wingspan of 3½–4 in. Female Monarchs have darker veins on their wings, and the males have a spot called the "androconium" in the center of each hind wing from which pheromones are released. Males are also slightly larger. The Monarch is famous for its southward migration and northward return in summer in the Americas which spans the life of three to four generations of the butterfly. The eggs are creamy white and later turn pale yellow. The caterpillar is banded with yellow, black, and white stripes. The head is also striped with yellow and black. The chrysalis is blue-green with a band of black and gold on the end of the abdomen. Monarchs are foul-tasting and poisonous due to the presence of cardenolide aglycones in their bodies, which the caterpillars ingest as they feed on milkweed.
The Monarch can be found in a wide range of habitats such as fields, meadows, prairie remnants, urban and suburban parks, gardens, and roadsides. It overwinters in conifer groves in Mexico.
A color variation has been observed in Australia, New Zealand, Indonesia and the United States as early as the late 1800s. 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. Monarch caterpillars only eat Milkweed, so it's important to plant this important plant in your gardens and protect areas where wild milkweed grow!