The body of the monarch butterfly is black, with white spots.

Male monarch have a distinct black androconial mark on the upperside of the hind wing. This is also called a scent patch because it is where the pheromones are released that attract females.

On the underside of the male's hind wing, the androconial mark is less disctinctive.

Female Monarchs have darker veins on their wings and lack scent-scale patches.

Adult Monarch Butterflies feed on the nectar of a variety of flowers, including milkweeds.

Monarch butterflies have siphoning mouthparts, i.e., they are used to suck up liquids. Like other butterflies, Monarchs have a long, tubular proboscis that is held coiled under the head when not in use. During feeding it is extended to reach into the flower and suck up the nectar.

Adult Monarch Butterflies mating

There's only one other butterfly that looks similar, the Viceroy. But it's easy to tell the two species apart by the pattern of the veins in the hindwing: In the Viceroy but not the Monarch they form a big curved line in the outer third of the wing.

The egg of a Monarch is dome-shaped and has longitudinal ridges.

Monarch larvae feed on milkweed (Genus Asclepias). They sequester substances called cardenolides, a type of cardiac glycoside, from their hostplant. Cardenolides are very toxic and protect both the larva and the adult butterfly from predators.

The bright colors of Monarch larvae probably function as warning colors. They let predators know that the larva is defended by toxins.

Monarch larva getting ready to pupate.

Monarch Butterflies are famous for their annual migration. They spend their winter in hibernation in Mexico or Southern California where it is warm all year long. Monarchs who spend their summers east of the Rocky Mountains, migrate to Mexico and hibernate in oyamel fir trees.

Monarch butterflies that spend their summer west of the Rocky Mountains, hibernate in and around Pacific Grove, California in eucalyptus trees.

Young Monarch Butterfly pupae are bright green.

The Monarch chrysalis (pupa) is adorned with small golden spots. Apparently, these spots are need for the normal development of the butterfly, but their function is not yet understood.

As the butterfly develops inside the chrysalis, the newly formed wings become visible through the pupal wall. The adult Monarch will soon eclose.

A freshly emerged butterfly with the wings expanded.

This butterfly has just emerged from its pupal skin and is in the process of pumping hemolymph into its wings to unfold them.