Monarch

Danaus plexippus

Copyright, T. W. Davies, California Academy of Sciences

The Monarch is one of our best-known butterflies. It is a large insect, growing up to four inches wide. Monarchs are bright orange with black veins and white dots. Underneath their wings, they are much paler. You can tell males from females, because males have thinner veins and two black spots on their hind wings. These spots release a smell to attract females.

Monarchs are usually seen in weedy fields, meadows, marshes, roadsides, and near water, such as streams, ponds, and lakes.

Copyright, Will Cook

Dale Clark

After mating, female Monarchs lay eggs, one at a time, on certain plants. They only lay eggs on plants in the milkweed family. These host plants are the only food Monarch caterpillars will eat.

Caterpillars hatch from a pale green egg and eat their own egg shell before starting on the host plant. Caterpillars continue to eat and grow, only leaving their host plant if they've eaten all the leaves and need to find a new milkweed.

Caterpillars grow up to two inches long. They are white with black and yellow stripes.

The leaves of milkweed plants are poisonous to most animals, because they contain chemicals called "cardenolides." Monarch caterpillars are not affected by cardenolides; in fact, they store these chemicals inside their bodies, which makes the caterpillars poisonous to most animals. Later, when the caterpillars turn into adult butterflies, the cardenolides stay inside.

Very few vertebrates (animals with backbones, such as mammals and birds) eat Monarch caterpillars or adults, although many will give them a try before spitting them out. From then on, the animal has learned that Monarchs aren't good to eat and they avoid them.

Invertebrate predators (animals without backbones, such as other insects), don't seem to mind the cardenolides so much. Therefore, Monarchs' main predators are insects, such as wasps, ambush bugs, and some species of stink bugs. Spiders also eat Monarchs. It is believed that some lizards and frogs (even though they're vertebrates) eat them too.

Mark Moran

Copyright, Dale A. McClung

Copyright, Dale A. McClung

When a caterpillar has had its fill of milkweed leaves, it looks for a place to pupate (resting stage). The name for a butterfly pupa is a chrysalis. A Monarch chrysalis is almost an inch long, jade green with gold spots, and plump. The adult Monarch butterfly will emerge from the chrysalis in a few weeks.

Adult butterflies drink flower nectar for food. Milkweed flowers are one good source of nectar, but these butterflies visit many other flowers too, including: clovers, thistles, goldenrods, ironweed, and sunflowers.

Monarchs are also interesting, because they are one of the few butterflies that migrate.

In early Fall, all of the Monarchs in our area form large groups and head South. They travel over 2000 miles to Mexico, where they will spend the winter. These butterflies will not make it back North. Instead, they mate, lay eggs, and die in Mexico.

The Monarch eggs laid in Mexcio hatch into caterpillars, which then pupate and become new Monarchs. In the spring, the young Monarchs begin flying North. These Monarchs won't make it to our area either, but they will mate and lay eggs along the way. It is the next generation of butterflies that makes it to us.

Mark Moran

Mark Moran

Some Monarchs live for months, and some only live for a few weeks. The butterflies that migrate South in the fall live the longest, up to eight months. Monarchs born here in early Summer only live a month or so, since they do not have to make a journey.

Monarchs are used as hosts by certain parasites, including tachnid flies and braconid wasps.

Monarchs also help some other species of butterflies. Some orange-colored butterflies, especially the Viceroy, are mimics of Monarchs. This means, even though Viceroys aren't poisonous, predators avoid them, thinking they are Monarchs. Viceroys gain protection just by looking like a Monarch.

Copyright, Will Cook

Additional Media

Description
Type
Credit
Monarch Caterpillar Eating (close up)
Video
Journey North (Annenberg/CPB)
Monarch Caterpillar Moving Up Stem
Video
Journey North (Annenberg/CPB)
Monarch Caterpillar Forming Chrysalis
Video
Journey North (Annenberg/CPB)
Adult Monarch Emerging from Chrysalis (very long)
Video
Journey North (Annenberg/CPB)
"Monarch Watch" website with lots of pictures and info
Link to Website
University of Kansas Entomology Program
"Monarch Butterfly" website with information, activities, and videos
Link to Website
Journey North (Annenberg/CPB)

Relationships in Nature:

 
FOOD
PREDATORS
SHELTER
OTHER

Common Milkweed

Bald-faced Hornet

Common Milkweed

Common Milkweed H Po

Red Clover

Eastern Yellow Jacket

Viceroy Mi

Bull Thistle

Goldenrod Spider

Red Clover Po

Goldenrod

Black and Yellow Argiope

Goldenrod Po

New York Ironweed

Spined Micrathena

Bull Thistle Po

Woodland Sunflower

New York Ironweed Po

Buttonbush

Woodland Sunflower Po

Relationship to Humans:

Monarchs are beautiful animals, and many people plant milkweed and other plants in order to attract them to their yards. Gardeners also like Monarchs, because they help control milkweed, which can be a pest when it crowds out other plants.

 

SCIENTIFIC CLASSIFICATION

KINGDOM
Animal
PHYLUM
Arthropod
CLASS
Insect
ORDER
Lepidoptera
FAMILY
Danaidae
GENUS
Danaus
SPECIES
Danaus plexippus

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