Geographical Range North America
Habitat Widely distributed through North America from spring through fall. Migrate to sites in California and Mexico for winter.
Scientific Name Danaus plexippus
Conservation Status Not listed by IUCN
Zoo Location Insectarium

Adult monarch butterflies have orange wings with black veins and black borders speckled with white spots. The caterpillars are yellow, black and white.

Life Cycle

The monarchs' scientific name, Danaus plexippus, is Greek for "sleepy transformation." Monarchs, like other butterflies and moths, undergo complete metamorphosis, meaning they have egg, larva (caterpillar), pupa (chrysalis) and adult stages.

Got Milk...weed?

Monarch caterpillars feed exclusively on milkweed plants. They eat and grow rapidly, increasing their weight almost 3,000 times in 10-15 days. The female lays her eggs on the milkweed plants because it is the only food the caterpillars can eat. Adult monarchs sip nectar from flowers.

The population of monarchs has declined by 90 percent in under 20 years, largely due to herbicides that have wiped out milkweed plants in Midwestern corn and soybean fields.

The Zoo has partnered with the City of St. Louis and other groups through the STL Milkweed for Monarchs Initiative to increase the dwindling monarch butterfly population and to better connect people and urban nature. Help maintain the monarch population by planting a native milkweed garden near you. 

Monarch Gardens for Schools Educator Guide, a resource guide for preK-12 urban school communities, was created by the Saint Louis Zoo in partnership with the Missouri Botanical Garden, U.S. Fish & Wildlife Service and the City of St. Louis. The guide was developed to provide St. Louis educators with the information and tools they need to create, expand, and enjoy school monarch gardens.

The Great Migration

During spring and summer, monarchs breed throughout the U.S. and southern Canada. In the fall, adults of an eastern population migrate to Mexico, flying up to 3,000 miles. Monarchs can travel between 50-100 miles a day; it can take up to two months to complete their journey to winter habitats. Monarch butterflies cannot fly if their body temperature is less than 86 degrees. They will sit in the sun or "shiver" their wings to warm up. Thousands can cluster on a single tree; a group of monarchs is called a "flutter." Monarchs west of the Rocky Mountains migrate to sites in central and southern California.

Fun Fact

The monarch butterfly is the state insect of Alabama, Idaho, Illinois, Minnesota and Texas, and the state butterfly of Vermont and West Virginia.