The Monarch butterflies are famous for their migration. In late march the population east of the Rocky Mountains starts north bound trip from Mexico. Early April Monarch butterflies stop over Florida and Texas to lay their eggs. Once they finish laying eggs on milkweed, they will die afterwards. Then a new generation will take over the journey.

Late May a new generation continues the journey to avoid heat. On their way to North they also lay eggs in the milkweed meadow. Early June finally the migration comes to end, when they reach southern Canada. The lifespan of most Monarch butterflies is less than a month. So two or three generations of Monarch will hatch out, lay their eggs and die until they start a southward migration in late August.

Female have darker veins (left), Males have dots on hind wings (right)

the dots on the male's hind wings

In late October they stop in Texas to get nutrition which is nectar of several kinds of plants such as swamp milkweed, asters, wild carrot and alfalfa.

In the middle of November millions of Monarch butterflies arrive in the state of Michoacan which is located in the central Mexican highlands. The last generation of the summer does not lay eggs and could live for 7 months or longer. They cluster together on Sacred fir over the winter.

The egg hatches after 3 to 5 days.

Since milkweed which the caterpillar feed on is poisonous to other animals, the caterpillar itself becomes poisonous too. Vivid color tells that I am poisonous. Adult Monarch butterfly is also poisonous. The caterpillar grows to about 5cm (2in), after 2 to 3 weeks they enter the next stage.

The pupa of Monarch butterfly

The population west of the Rocky Mountains stays in Pacific Grove, California during the winter.

Monarch butterflies are also found in Hawaii, New Caledonia, New Zealand, Australia, New Guinea, India and the Canary Islands.