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This is a Monarch butterfly. Butterflies and moths belong to the order Lepidoptera.
Monarchs depend on milkweeds because they are the only plants that monarch caterpillars
can eat. The adult butterflies drink the nectar of flowers. The monarch butterfly contains
milkweed poisons that it ate when it was still a caterpillar.
The monarch is the only butterfly that migrates for very long distances like some birds do.
During the fall migration, sugars from nectar are stored as fat in the butterflyís abdomen.
This fat is necessary fuel for the butterflies to complete their migration and overwinter
successfully. In the late summer and early fall of each
year, shorter days and cooler temperatures tell the monarch butterflies not to breed,
but instead, to begin their long migration. The monarchs that emerge in September and
early October are the migrants. They will live six to eight months. Because they are
the great-grandchildren of the butterflies that flew north the previous spring, they
have never been to the overwintering sites in California or Central Mexico. And yet somehow,
they find their wayóprobably through an inherited behavior pattern.
The monarchsí overwintering sites in the forests of the mountain ranges in Central
Mexico are about 10,000 feet, or 3,000 meters, above sea level. The tall trees make a thick
canopy, helping to protect the monarchs from wind, snow, rain, or hail. Fog and clouds
settle on the trees and provide moisture. To conserve energy, the butterflies cluster
on trees where the temperature is just above freezing. They cover whole tree trunks and
branches. Hundreds of millions of butterflies can overwinter in Mexico in one year.
On the forest floor, the butterflies find nectar sources among the flowering plants.
On sunny days, the butterflies often warm up enough to fly to nearby creeks and puddles
where they drink water. Monarchs begin mating as the weather warms
in the spring. By early March they fly back north in masses. The females must find early
sprouts of milkweed on which to lay their eggs.