Monarch butterfly

The monarch butterfly (Danaus plexippus) is a large orange-and-black butterfly found across North, Central, and parts of South America, with introduced or established populations in other regions.

The monarch butterfly (Danaus plexippus) is a large orange-and-black butterfly found across North, Central, and parts of South America, with introduced or established populations in other regions. It is best known for its long seasonal migration in North America and for its dependence on milkweed during the caterpillar stage.

Description

Monarch butterflies are large butterflies with vivid orange-and-black wings and white-spotted borders. Males and females are similar in appearance, though sources note some differences in wing vein thickness and hindwing markings.

Life cycle

Monarchs pass through four stages: egg, larva, pupa, and adult. Several generations are produced each year, and the late-summer generation is the one that undertakes the long southward migration.

Migration and range

The best-known monarch populations breed in the United States and southern Canada and overwinter in Mexico, while western monarchs overwinter in coastal California. Monarchs also occur year-round in some warm climates and have spread beyond their native range.

Ecology and defense

Milkweed is the sole food plant for monarch caterpillars and is the source of the toxins that protect adults from predators. Adults feed on nectar from many flowers and are important pollinators, though not especially effective milkweed pollinators.

Conservation

Monarch numbers have declined substantially in North America, with habitat loss and loss of milkweed among the main pressures cited by conservation groups. The migratory monarch was listed as endangered by the IUCN in 2022.