Monarch Butterfly on Milkweed

Monarch Butterfly

Monarch Butterfly Picture

You can’t raise Monarchs without the Milkweed family of plants. It is the sole Monarch caterpillar food source.

There are over 100 species of milkweed in North America. They are members of the genus Asclepias.

The thick, white milk (sap) of the milkweed family of plants contains lethal cardenolides (heart poisons).

They produce vomiting and sometimes death if eaten by a predator.

The Monarch’s tissues are miraculously not harmed by the chemicals which normally effect the nervous system.

This means the Monarch:

  • has few competitors for milkweed
  • caterpillar, after eating milkweed, has higher concentration of poisons than the plant
  • poisons are passed from caterpillar to butterfly during metamorphosis
  • predators stay away after one taste, however, Cardinals seem to think they are very tasty!

The Monarch’s total dependency on milkweed also means “no milkweed……no Monarch”.


Photographed by Craig Glenn on Milkweed in our backyard.

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