Range

The Monarch butterfly is native to the Americas. They are known for the large migrations which the species undertake each year. They breed during summer in the North and then move to the South for Winter.

At present there are two main populations of the species. The first will breed in the western Rocky Mountains and fly to southern California for winter. The others live in the Great Plains and Canada before flying to Mexico for winter.

Populations now also exist in Hawaii, Portugal, Spain, Australia, the United Kingdom New Zealand and other pacific islands. Some of these populations may have reached these locations naturally either by island hopping or on a storm front.

Habitat

They are found mostly in mountainside forests. They are able to live in almost any environment where their food plant of milkweed is present.

Reproduction

Mating takes places primarily in Spring. This can occur year round though with the only break in their breeding season being prior to Winter when they are about to migrate.

Males will transfer a spermataphore to the female which she uses both to fertilize the eggs and to provide the nutrients needed to produce the eggs. Each female may lay 300-500 eggs.

Once mating is complete the female starts to lay her eggs on a milkweed plant. These are stuck on a with a special glue produced by the female. Once the eggs hatch they are able to eat the milkweed and begin to grow.

They spend two weeks in the caterpillar stage during which they have a long thin body with many legs. This is coloured with yellow, black and white stripes.

At the end of this 2 week period the monarch butterfly will form a chrysalis which is a protective case around them and they begin their pupal stage.

Two weeks later they finish their pupal stage and begin the metamorphosis in to an adult butterfly.

Behaviour

Monarch butterflies are most notable for their annual migration. The adults move South over winter. To achieve this they store fat so they don’t need to eat on the way. A similar migration is also undertaken by the population which has established in Australia.

Predators and Threats

Most species are unable to eat the Monarch butterfly as they are poisonous. Some such as wasps and birds are able to tolerate them though. The oriole will eat the butterfly and once it is down they vomit to bring up the poison.

Their bright colour acts as a warning to other animals that they are poisonous and should not be eaten.

Humans have had a large effect on their population. This is through the use of chemicals and the removal or poisoning of milk weed as it can make livestock ill. Logging in the areas which they use to overwinter also threatens them as it leaves them more susceptible to wind and rain.

Quick facts

One area where the Monarch butterflies overwinter known as, The Monarch Butterfly Biosphere Reserve is now a World Heritage Site.

Some of the spots where the monarch butterfly gathers in large numbers have become a tourist attraction.