[ Danaus plexippus ]

Quick Facts

WING SPAN: 3 to 5 inches
WILD DIET: nectar from flowers, milkweed
ZOO DIET: nectar from flowers, milkweed

North America, south of Hudson Bay down to South America; also have been established in Hawaii and Australia


open fields and meadows in spring and summer; coast of southern California and at high altitudes in central Mexico in winter

Got Milkweed?


In its larval or caterpillar stage, monarch butterflies rely on milkweed. In fact, it’s pretty much all they consume until they become adults and switch to drinking nectar from flowers.


Milkweed, naturally, does a [butterfly] body good. But it also keeps them from harm, too. In its many varieties, milkweed contains alkaloids which build up in the monarch’s body and can be poisonous to other animals. Consequently, when birds and other insect-eating predators decide to chomp down on a monarch or its larva, they might be shocked by a horrible taste. The alkaloids can even cause some animals to vomit.



Viceroy butterflies offer monarchs the best form of flattery: imitation by adaptation! They seem to have realized that predators steer clear of the orange fliers, so the viceroys have similar “monarch” markings as a possible survival tactic.


Egg to adult

Butterflies, like moths, go through metamorphosis in a cycle of four life changes. First, monarch moms lay their eggs one by one—typically on the underside of milkweed leaves. Three to six days later, the eggs hatch into tiny caterpillars. After nine to 14 days (and the shedding of several layers of skin), they become full grown at about two inches long.


Each caterpillar then leaves the milkweed plant and crawls up to 40 feet away to a safe place where it enters the pupa, or chrysalis, stage of metamorphosis. During this stage, the chrysalis—which is the smooth, green casing underneath the caterpillar’s skin—hardens and acts as a protective shell. Over the next nine to 14 days, the caterpillar transforms into a butterfly, developing the mouth parts (proboscis for sipping nectar), wings, and other adaptations needed to survive on the fly.


Journey of generations

In the monarch’s summer territory, in most of North America, a butterfly’s life lasts from two to six weeks. During that period, they mate around seven times and produce large groups of young. When the fall approaches, the last monarchs that develop are non-reproductive. Instead, they are equipped for migration.

Storing fat in their abdomen for energy, these butterflies travel south to southern California and Mexico. When they arrive, they are so tired from their journey that they cluster together in trees, in groups of thousands, and stay almost perfectly still feeding off their stored fat. This lasts until about mid-February when they break up and begin feeding on nectar. When spring arrives, they enter their first mating season and produce young that will migrate back north.

Monarch butterflies at Brookfield Zoo

Over 40 different species of butterflies color the sky at Brookfield Zoo’s seasonal exhibit. Open Memorial Day through mid-September, Butterflies!—a screened, outdoor flower garden—offers guests the opportunity to encounter monarchs, their viceroy pals, and many other winged wonders.

Get Involved

Conservation Fund of the Chicago Zoological Society