Four Stages of the Monarch Butterfly Life Cycle
Monarch butterflies are one of the most beloved butterflies and insects in North America. They are well known for their vibrant colors which are used as a warning sign to their predators.
Monarch butterflies go through four stages during a complete life cycle. The stages are comprised of eggs, caterpillar (larvae), chrysalis (pupa), and adult butterfly. Below I will describe each of the stages that the monarch will go through during its life span.
Eggs
The female monarch butterfly will lay her eggs on the only host plant for monarch butterflies which is milkweed. She will lay her eggs underneath the leaf or on the stem of the milkweed plant. It usually takes 4 to 5 days for the eggs to change into a first instar caterpillar. The monarch egg is oval and opaque and very tiny like the size of a pen head. When the egg starts to darken, this indicates a first instar caterpillar is about to emerge from the egg.
Caterpillar (Larvae)
During the caterpillar stage of the life cycle, the monarch caterpillar will have 5 phases, called instars, before they began their next phase. When the caterpillar emerges from the egg, it will begin its first instar phase. These first instar caterpillars will begin by eating the shell of the egg from which it hatched before moving on to their host plant, milkweed.
During each of the 5 instar phases the caterpillar will continue to eat more and more, and when they become to large for their skin, they will molt or shed their skin. The caterpillar usually will eat that skin and then resume eating away at the milkweed leaves. Sometimes when the leaves of the milkweed plant all are eaten, the caterpillars will eat on the stem of the milkweed.
During these five instar phases, the caterpillar will do all of its growing, feeding exclusively on milkweed. During each instar phase the caterpillar will grow bigger and antennae-like tentacles will develop at each end of their body. Those tentacles will get longer at each instar phase. In total, these five instar phases will last about 10-14 days before the monarch caterpillar begins to pupate.
Chrysalis (Pupa)
Once the caterpillar is a 5th instar, it begins to look for a place where it can become a chrysalis or pupa, the fourth life cycle. Usually the location is out of direct sunlight and will be anywhere from the side of the house to a wooden fence, garden pots, or wooden structures like a underneath a butterfly house in the garden. Often the location of where the chrysalis is formed is far away from where they feed on their host plant of milkweed.
The caterpillar will seek a place safe from predators or the elements. At a suitable location the caterpillar from the spinneret on the bottom of its head will spin a silk mat or attachment from which it will then hang upside down from their back legs. It puts its stem-like cremaster into the silk pad from which to hang.
The caterpillar then sheds its skin from the rear end, thus creating a bright green chrysalis. Inside the chrysalis it undergoes a transformation with its organs and body parts. The chrysalis stage of the life cycle of the monarch will last anywhere from 10-14 days.
When the monarch chrysalis turns black with its beautiful orange and black wing coloring being seen, the adult butterfly will be born the next day.
Adult Butterfly
Usually, the adult butterfly emerges from its chrysalis in the morning. Once emerged, it will be all crumpled up with wet wings and will need time to hang on or near its empty chrysalis for at least an hour or maybe two hours for its wings to dry out. During this time the butterfly continues to grow as its wings become drier.
While the emerged monarch is drying its wings and still growing outside of the empty chrysalis, it is important that the location is not in direct sunlight. If the monarch butterfly wings dry to quickly, they may have crippled wings, and therefore, they would be unable to fly or survive in the wild.
Nearly six weeks after the monarch egg is laid an adult butterfly emerges from the chrysalis. Male and females look the same except for one distinctive feature. The male has two black spots on the surface of each hindwing, and the female does not have these two black spots.
The stages of their life cycle from egg to larva to pupa to adult is called a complete metamorphosis. Adult monarchs live between 2 to 6 weeks. Females and males will mate and eggs will be laid throughout most of this period. However, the migrating monarch butterflies will live up to 8 months.
Since the monarch butterfly migrates, the last generation of monarch’s from each year will have a longer lifespan. These adult butterflies born in the late summer will migrate to their overwintering areas. The Eastern monarch butterfly will migrate to Mexico, while the Western monarch butterflies will overwinter in California.
The female adult butterfly will lay up to 300 eggs on milkweed plants during her brief lifespan. This is why it is important for us to provide the milkweed plants so that the female adults will be able to lay their eggs allowing the life cycle to repeat with another generation of monarch butterflies.
The monarch life cycle repeats until the fourth generation, which is the monarch butterfly that migrates for the winter. The first generation of Eastern monarchs will be the ones that migrate from Mexico to the east coast of the southern United States. The second and third generations will emerge through the summer months to lay eggs as they migrate north in the Eastern United States. The fourth generation of monarchs will the ones that will fly nearly 3,000 miles in the migration to the Transvolcanic mountains of central Mexico.
Normally, it would take monarch butterflies about 4 to 6 weeks to transition through their life cycle from egg to adult. Sometimes, temperatures during the summer months may influence how long their life cycle actually takes. With the influence of the temperatures this could allow for additional monarch generations during the summer months before their migration begins.
These beautiful and precious butterflies are declining in population. They need our help by providing them nectaring flowers for food for the adults, lots of milkweed plants for egg-laying and for food for the caterpillars, and places of shelter for their chrysalises.
Adult monarch butterflies need nectar from various flowers so that they can maintain their nourishment and to fuel up for flying.
Each summer the monarch butterflies may have up to four generations as each generation travels farther north from the previous generation. However, the last generation that is born in the late summer will be the generation that will migrate to the overwintering sites in Central Mexico for the Eastern monarch population and to California for the Western population.
