Range
Wherever there is milkweed there will be Monarch butterflies. The monarch is widely distributed across North America, from Central America northwards to southern Canada, and from the Atlantic to the Pacific coasts. Three geographically distinct populations make up the total North American range of the species, one each both east and west of the Rocky Mountains, and one Central American. Each of these populations has a distinct migratory pattern. Monarchs that live west of the Rocky Mountains will migrate to southern California for winter while monarchs that live east of the Rockies will migrate to Mexico.

Where do monarchs form their roosts?
"I've been experimenting with finding roosts," says Mr. Tom Murphy of Minnesota. "I think the key is to find a nectar source. Even when migrating hard, monarchs need to stop for a sip."

What causes roosts to come and go?
An observer counted the number of monarchs that roosted in his yard each night. The graph below shows the pattern he noticed. What might cause the number of monarchs to change this way?

Here is what the observer noticed:
"The roost grew bigger and bigger when the wind was from the south. When the wind blew from the north the numbers dropped."

How long does one butterfly stay at a roost?
People often tag monarchs hoping to find out how long individual butterflies stay at a roost. The person who tagged the two butterflies pictured here wondered: For how many days will these same butterflies be here—and will I be able to find them?

How do the butterflies find the roost?
Few people have had the chance to watch a roost form. One observer described it this way:

"The air resembled a monarch airport, with monarchs coming in from every direction, floating through the air, checking out various trees, landing, then taking off again. It took from about 7:15 to 7:35 p.m. for them to cluster in the trees, just before dark."

Why do roosting monarchs flash their wings?
When a butterfly approaches a cluster, the roosting butterflies flash their wings. What does this behavior signal?

Why do monarchs form roosts?
Scientists still have many questions about roosting behavior. Dr. Lincoln Brower has studied monarchs for over 50 years. He knows that roosting must be critical for monarch survival. How would Dr. Brower search for answers?

Diet...
In their larval stage monarch caterpillars feed almost exclusively on milkweed and as adults get their nutrients from the nectar of flowers. The monarch will always return to areas rich in milkweed to lay their eggs upon the plant. The milkweed they feed on as a caterpillar is actually a poisonous toxin and is stored in their bodies. This is what makes the monarch butterfly taste so terrible to predators.

Behavior....
Monarchs can produce four generations during one summer. The first three generations will have life spans from 2 - 6 weeks and will continue moving north. During this time they will mate and have the next generation that will continue the northward migration. The fourth generation is different and can live up to nine months. These are the butterflies that will migrate south for winter to either Mexico or southern California.

February/March - hibernating monarchs in Mexico and southern California reawaken, become active, find a mate, begin the flight northward and lay their eggs. Finally they die. These special monarchs have lived about 4-5 months through the long winter.

March/April -the 1st generation monarchs are born -egg, caterpillar, chrysalis, adult butterfly;

May/June - the 2nd generation is born - egg, caterpillar, chrysalis, adult butterfly;

July/August - the 3rd generation is born - egg, caterpillar, chrysalis, adult butterfly

Sept/Oct - the 4th generation is born - egg, caterpillar, chrysalis, adult butterfly . . . but THIS generation does not die. It MIGRATES south and lives 6-8 months in Mexico or Southern California. They begin awakening and mating in February/March of the NEXT SPRING, and then lay their eggs! Withered and tattered from their migration and hibernation . . . they finally die.
The cycles goes on as the new baby caterpillars are born each spring and the cycle continues throughout the year into the next spring. MAGICAL and AMAZING!