Monarch eggs are always laid on milkweed. The caterpillars will feed solely on any variety of this plant. Common or Swamp Milkweed, as well as Butterfly Milkweed are host plants for Monarchs.
The caterpillar will develop inside the egg for about five days.
Empty Monarch egg
Newly-hatched Monarch Caterpillar Eating Its Egg Shell
Often the first meal of the caterpillar is the shell of its egg. Likewise, the growing caterpillar will consume its shed skin as it molts.
Monarch caterpillar, First Instar
The caterpillar consumes the milkweed in layers, until it has eaten a hole through the leaf.
Monarch caterpillar on milkweed leaf
Monarch Caterpillar on Milkweed
Large Monarch Caterpillar
the Monarch caterpillar goes through five instars (the life phase between molts). During this time, which lasts from one to two weeks, depending on weather, the caterpillar eats almost constantly, and grows from 3-6 mm in its first instar to 25-45 mm in the fifth.
Monarch Caterpillar Ready to Pupate
When the caterpillar is ready to pupate it attaches itself to a surface from a silken pad it spins at its back end.
New Monarch Pupa
When the caterpillar molts for the last time the pupa is exposed. It is soft and very vulnerable at this early stage.
Soon the pupa hardens into a beautiful green and gold chrysalis. This stage lasts anywhere from one to two weeks.
Just before the butterfly emerges the butterfly becomes visible within its chrysalis.
Monarch Butterfly Adult
Adult Monarch butterflies feed from many nectar plants. They seek mates and lay eggs. The summer generations of adult Monarchs live anywhere from two weeks to about a month. The final generation will live much longer, up to nine months. Their long lives make their amazing migration possible. These butterflies migrate great distances. Eastern Monarchs travel to Mexico, western Monarchs to California.
Migrating Monarch Butterfly