Monarch Butterfly (Danaus plexippus)
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Monarchs are primarily known for their long migration every spring and fall to reach either their summer breeding grounds in the United States and Canada, or their winter resting grounds in Mexico.
There are distinct Monarch populations east and west of the Rocky Mountains, and it might be a new fact to some people that there are populations of monarch butterflies that winter in Southern California. You can drive down the Pacific Coast Highway and find their wintering grounds in areas such as Pismo Beach.
Monarch butterflies are members of the Nymphalidae family, more commonly known as the brush-footed butterflies.
Within the brush-footed category, they are further classified as milkweed butterflies, because their larvae feed on milkweed plants. The Queen Butterfly is also a member of this sub-family.
Field identification is usually easy. They have orange wings, outlined in black, and white spots on a black face.
Monarch butterflies made a good deal of news starting in 1999, when a researcher from Cornell University conducted a laboratory study on the effect of Bacillus thuringiensis (BT), a natural insecticide, on the monarch butterfly. BT properties were being bred into some genetically altered corn varieties to deal with the European corn borer. Since milkweed and cornfields grow together, the fear was that monarch butterfly caterpillars were susceptible to harm, even to death, when they ingested milkweed leaves dusted with pollen from genetically engineered Bt corn.
The research brought on a wave of press attention questioning the safety of BT crops. Follow up research shows little harm to monarch populations to date.
© 2003-2007. Patricia A. Michaels