Monarch

Most breeding adult butterflies live approximately two to five weeks, but overwintering adults that enter into reproductive diapause can live six to nine months.

Monarchs begin their lifecycle as eggs, which are laid on milkweed plants and hatch after two to five days. The eggs hatch into caterpillars and progress through five instars over the next two weeks before pupating into a green and gold chrysalis. An adult monarch will emerge one to two weeks later.

As temperatures warm at the overwintering sites in the spring, monarchs begin to breed and lay eggs on milkweed throughout their spring journey. The following generations breed and lay eggs throughout the spring and summer. In the fall, monarchs enter a state where they stop reproducing, known as diapause. This allows them to focus their energy and resources on the long-distance migration and surviving the winter. Some non-migratory monarchs in warmer climates breed year-round.

On average, adult monarch butterflies weigh about half of a gram, which is less than the weight of a paperclip.

The large and brightly colored monarch butterfly has two sets of wings that span three to four inches. Monarch caterpillars, or larvae, have black, yellow and white stripes and reach lengths of two inches before metamorphosis. Monarch caterpillars then pupate into a green and gold chrysalis and emerge six to 14 days later as adult butterflies.

Compared to monarchs from most non-migratory populations, monarchs from the eastern North American migratory population have unique physical characteristics, tending to have larger bodies and larger, elongated wings. In addition, the eastern North American migratory monarchs tend to have redder coloration, a trait associated with their ability to fly for longer periods of time. The mechanism for this correlation is unknown.

Measurements:
Wingspan: 3 to 4 inches (7 to 10 cm) 
Larval length: 2 inches (5 cm)

Adult monarch butterflies are large and conspicuous, with bright orange wings surrounded by a black border and covered with black veins. The black border has a double row of white spots, present on the upper side of the wings. Adult monarchs are sexually dimorphic, with males having narrower wing venation and scent patches. The bright coloring of a monarch serves as a warning to predators that eating them can be toxic.

The large and brightly colored monarch butterfly has two sets of wings that span three to four inches. Monarch caterpillars, or larvae, have black, yellow and white stripes and reach lengths of two inches before metamorphosis.   

Measurements: 
Wingspan: 3 to 4 inches (7 to 10 cm) 
Larval length: 2 inches (5 cm) 

Whether it’s a field, roadside area, open area, wet area or urban garden, milkweed and flowering plants are needed for monarch habitat. Adult monarchs feed on the nectar of many flowers during breeding and migration, but they lay eggs on milkweed plants as that is the only food the caterpillars can eat.

For overwintering monarchs, habitat with a specific microclimate is needed for protection from the elements, as well as moderate temperatures to avoid freezing. These conditions vary between populations.

For the eastern North American population, most monarchs overwinter in oyamel fir tree roosts located in mountainous regions of central Mexico, at an elevation of about 8,000 to nearly 12,000 feet (2,400 to 3,600 meters) - over two miles up!

Monarchs living west of the Rocky Mountains in North America primarily overwinter in California at sites along the Pacific Coast, roosting in eucalyptus, Monterey pines and Monterey cypress trees.

Adult butterfly species that look similar to the adult monarch are soldier butterfly (Danaus eresimus), queen butterfly (Danaus gilippus) and the viceroy (Limenitis archippus).

The monarch butterfly’s annual fall migration is one of nature’s greatest phenomena. The monarch's journey is one of the longest known insect migrations in the world. Each fall, the eastern and western North American monarchs go into a state of suspended reproduction, known as diapause, and begin migrating to their respective overwintering sites. The eastern population of monarchs travel up to 3,000 miles during migration traveling from Canada, through the U.S. and down to Mexico - a trip that may last more than two months. Tagging and observational data suggest that monarchs can travel up to approximately 70 to 75 miles a day during migration. The longest single day flight of a tagged eastern North American monarch was recorded at 265 miles.

In early spring, surviving monarchs break diapause and mate at the overwintering sites before dispersing. The same individuals that undertook the initial southward migration begin flying back through the breeding grounds. After several generations of monarch offspring in the spring and summer, a new generation begins the fall migration for the first time.

With the year-round presence of milkweed and suitable temperatures, monarchs in many areas of the their worldwide range, including parts of North America, live and breed year round. Many of these non-migratory monarchs are genetically distinct from the migratory North American monarchs, although the southern Florida population gets an annual influx of individuals from the eastern monarch population.

Monarch butterflies require healthy and abundant milkweed plants for both laying eggs on and as a food source for caterpillars. By consuming milkweed plants, monarchs obtain toxins, called cardenolides, that provide a defense against predators. Additionally, a wide variety of blooming nectar resources (flowers) are needed for adults throughout the breeding season, migration and overwintering.

In western North America, nectar and milkweed resources are often associated with riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian corridors, and milkweed may function as the principal nectar source for monarchs in more arid regions.