Monarch Butterfly

Danaus plexippus

Description

Monarch butterflies are bright orange with black and white markings. The body of the monarch is black. The head has a set of antennae.

The wings are mostly orange with black veins running throughout. The outer edge of the wings has a thick black border. Within the black border are white spots. The white spots can range in size and they decorate the wings. At the upper corner of the top set of wings are orange spots.

The underside of the monarch butterflies’ wings can be seen when the butterfly is at rest or when it is feeding on a flower. Instead of bright orange, the underside is more drab and orange-brown.

Males and females can be told apart by looking at the top of their hind wings. Males have a black spot at the center of each hind wing, while the females do not. The spot is a scent gland that helps the males attract female mates. Another less accurate way to tell males from females is that the females usually have much thicker veins than the males.

Monarch butterfly caterpillars are also easy to identify. The caterpillars have many yellow, black and white bands. There are antenna-like tentacles at each end of the caterpillar’s body.

Size

Monarch butterflies have a wingspan of 3 ½ – 4”

Habitat

Monarch butterflies utilize different habitat in the warm months versus the cold months. In the spring, summer and early fall, they can found wherever there are milkweeds. Monarchs lay their eggs on the milkweeds and they’re always searching for them in fields, meadows and parks. Many people plant milkweeds in their gardens.

Monarchs cannot survive freezing temperatures, so they over-winter in the cool, high mountains of central Mexico and woodlands in central and southern California.

Range

Monarch butterflies can be found throughout the United States, including Hawaii.

The majority of monarch butterflies live east of the Rocky Mountains. In the early spring, they are first seen in Texas and the south. As spring turns to summer, they’re seen in more and more states and Canada.

A much smaller population of monarch butterflies lives west of the Rocky Mountains. Instead of making the long journey between Mexico and Canada, the western monarchs only travel as far south as San Diego. Some monarchs live in California year-round and others spend summers as far north as British Columbia, Canada.
Hawaii also has monarch butterflies. Monarchs that were released or lost their way from California have found success year-round on the Hawaiian Islands.

Communication

Monarch butterflies communicate with scents and colors.

• The males attract females to mate by releasing chemicals from scent glands on the hind wings.
• All monarchs signal that they are poisonous by having bright orange wings. The bright colors serve as a warning that predators should attack at their own risk.

Diet

Monarchs, like all butterflies, change their diet as they develop. During the caterpillar stage, they live exclusively on milkweed plants. Milkweeds are wildflowers in the genus Asclepias. Milkweeds contain glycoside toxins that are harmless to the monarch but poisonous to its predators. Monarch caterpillars feed on all the different parts of milkweed plants and store up the toxins in their body. The toxins remain in their system even after metamorphosis, thereby making adult monarchs poisonous as well.

Adult monarchs feed on nectar from a wide range of flowers, including milkweeds.

The Life Cycle(s) of a Monarch Butterfly

Monarch butterflies go through 4 stages during one life cycle, and through 4 generations in one year. It’s a little confusing but keep reading and you will understand. The 4 stages of the butterfly life cycle are the egg, the larvae (caterpillar), the pupa (chrysalis), and the adult butterfly. The 4 generations are actually 4 different butterflies going through these 4 stages during one year until it is time to start over again with stage one and generation one.

In February and March, the final generation of hibernating monarch butterflies comes out of hibernation to find a mate. They then migrate north and east in order to find a place to lay their eggs. This starts stage one and generation one of the new year for the monarch butterfly.

In March and April the eggs are laid on milkweed plants. They hatch into baby caterpillars, also called the larvae. It takes about 4 days for the eggs to hatch. Then the baby caterpillar doesn’t do much more than eat the milkweed in order to grow. After about 2 weeks, the caterpillar will be fully-grown and find a place to attach itself so that it can start the process of metamorphosis. It will attach itself to a stem or a leaf using silk and transform into a chrysalis. Although, from the outside, the 2 weeks of the chrysalis phase seems to be a time when nothing is happening, it is really a time of rapid change. Within the chrysalis the old body parts of the caterpillar are undergoing a remarkable transformation, called metamorphosis, to become the beautiful parts that make up the butterfly that will emerge. The monarch butterfly will emerge from the pupa and fly away, feeding on flowers and just enjoying the short life it has left, which is only about 2 to 6 weeks. This first generation monarch butterfly will then die after laying eggs for generation number 2.

The second generation of monarch butterflies is born in May and June, and then the third generation will be born in July and August. These monarch butterflies will go through exactly the same 4 stage life cycle as the first generation did, dying 2 to 6 weeks after it becomes a beautiful monarch butterfly.

The fourth generation of monarch butterflies is a little bit different than the first 3 generations. The fourth generation is born in September and October and goes through exactly the same process as the first, second and third generations except for one part. The fourth generation of monarch butterflies does not die after 2 to 6 weeks. Instead, this generation of monarch butterflies migrates to warmer climates like Mexico and California and will live for 6 to 8 months until it is time to start the whole process over again.

Life History and Reproduction

Over-wintering monarch butterflies in Mexico begin to make the journey north to the United States in early spring. Soon after they leave Mexico, pairs of monarchs mate. As they reach the southern United States, females will look for available milkweed plants to lay eggs.

The eggs hatch after approximately 4 days. The caterpillars are small and they grow many times their initial size over a 2 week period. The caterpillars feed on the available milkweed plants. When they get big enough, each caterpillar forms a chrysalis and goes through metamorphosis.

The chrysalis protects the monarch as it is going through the major developmental change of turning from a caterpillar to a butterfly. The chrysalis is green with yellow spots. After another 2-week period, an adult butterfly will emerge from the chrysalis.

The adult monarchs continue the journey north that was left unfinished by their parents. Each year, about 4 generations will be born to continue migrating north. It is only the last generation, born in late summer that will live 8 months and migrate back to Mexico to start the cycle over again.

References

www.learnaboutnature.com – The Monarch Butterfly
www.nwf.org/Wildlife-Library/Invertebrates/Monarch-Butterfly.aspx