The annual monarch life cycle and migration begins at the monarchs’ overwintering grounds in Mexico (for the eastern population) and the central to southern California coastal region (for the western population). This migratory generation can live upward of eight months. The last generation that hatches in late summer delays sexual maturity and undertakes a spectacular fall migration, one of the few insects to do so. Most adult monarchs only live for a few weeks, searching for food in the form of flower nectar, for mates, and for milkweed on which to lay their eggs. After approximately another two weeks within the chrysalis, they emerge as adult butterflies. The caterpillars grow and molt several times over roughly a two-week period and then form a chrysalis in which they undergo metamorphosis. After hatching and consuming their empty egg case, monarch caterpillars feed exclusively on milkweed. It takes three to five days for the egg to hatch. Monarchs lay their eggs on milkweed, their only caterpillar host plant. These populations are not part of the annual migrations on the North American mainland. Monarchs may have been blown to these place in storms or naturally dispersed there by island-hopping, or they may have been introduced by humans. There are populations of monarchs in Hawaii, Puerto Rico, and some islands of the Caribbean, as well as in New Zealand. Instead of making the long journey to Mexico, western monarchs only migrate as far south as coastal areas of central and southern California. A small number of monarchs can be found in the coastal Pacific Northwest during summer months. During summer, western monarchs live in canyons or riparian areas of the West, Southwest, inland California, and the inland Northwest states up to British Columbia. Florida is a stop for many monarchs before they fly over the Gulf Coast to Mexico.Ī much smaller population of monarch butterflies lives west of the Rocky Mountains. Monarchs from the Northeast head south along the Atlantic coast, concentrating in the states that make up the Delmarva Peninsula between the Atlantic Ocean and the Chesapeake Bay on the journey. By late summer, eastern monarchs have spread north into Canada and eastward from the central migratory corridor throughout the Northeast and Southeast states.įrom September into early October, fall southern migration to Mexico begins, with the majority of monarchs following the reverse path south along the central migratory corridor.

In spring the monarchs leave overwintering grounds in Mexico and migrate north into Texas and the Southern Plains, then up through the Northern Plains and the Midwest, and finally up into the Great Lakes region. They are found in the highest concentrations along a migratory flyway corridor through the central United States. The population east of the Rocky Mountains contains the majority of the North American monarch population, which completes its northward migration through successive generations. In the fall the eastern population migrates to the cool, high mountains of central Mexico and the western population migrates to coastal California, where they spend the entire winter. In the summer they range as far north as southern Canada.

They are one of the few migratory insects, traveling great distances between summer breeding habitat and winter habitat where they spend several months inactive. Whether monarchs are present in a given area within their range depends on the time of year. They are broken into two populations separated by the Rocky Mountains, called the eastern and the western populations. Monarch butterflies are found across North America wherever suitable feeding, breeding, and overwintering habitat exists.

The monarch chrysalis, where the caterpillar undergoes metamorphosis into the winged adult butterfly, is a beautiful seafoam green with tiny yellow spots along its edge. They have a set of antennae-like tentacles at each end of their body. Monarch caterpillars are striped with yellow, black, and white bands, and reach lengths of two inches (five centimeters) before metamorphosis.

The butterfly’s body is black with white markings. Females have thicker wing veins than males. These spots are scent glands that help males attract female mates. Male monarchs have two black spots in the center of their hind wings, which females lack. The underside of the wings is pale orange. Their wings are a deep orange with black borders and veins, and white spots along the edges. They have two sets of wings and a wingspan of three to four inches (7 to 10 centimeters). The large and brilliantly-colored monarch butterfly is among the most easily recognizable of the butterfly species that call North America home.

Monark caterpillar