The Butterfly Brigade

Every fall, millions of monarch butterflies flock to the forests of central Mexico, where they will spend the winter. The orange-and-black insects cluster together, blanketing tree trunks and branches.

The monarchs’ arrival in Mexico also coincides with a big yearly celebration: Día de los Muertos, or Day of the Dead. During this holiday, held on the first two days of November, many families in Mexico visit cemeteries. They light candles and leave offerings of food to honor the memories of relatives and friends who have died. Monarchs—along with papier-mâché skeletons, marigold flowers, and sugar skulls—are symbols of the holiday. Some people say the butterflies carry the souls of departed loved ones, according to Lucía Romero Vásquez of the Communal Land Council. This belief about migrating butterflies traces back to the Aztecs, who inhabited central and southern Mexico from the 1300s through the early 1500s.

Every fall, millions of monarch butterflies flock to central Mexico. They will spend the winter in the forests there. The orange-and-black insects cluster together. They cover tree trunks and branches.

The monarchs arrive in Mexico at the time of a big yearly celebration. It is Día de los Muertos, or Day of the Dead. It takes place on the first two days of November. During this holiday, many families in Mexico visit cemeteries. They want to honor the memories of deceased relatives and friends. So they light candles and leave food offerings. Papier-mâché skeletons, marigold flowers, and sugar skulls are symbols of the holiday. So are monarchs. Some people believe the butterflies carry the souls of departed loved ones, says Lucía Romero Vásquez of the Communal Land Council. This belief about migrating butterflies goes back to the Aztecs. They lived in central and southern Mexico from the 1300s through the early 1500s.

The council Vásquez is a part of manages the 100-acre Joya Redonda Monarch Butterfly Sanctuary near the town of San Miguel Atlautla. Town residents began noticing large numbers of monarchs settling on the area’s oyamel fir trees 15 years ago. This was a few hundred kilometers east of the butterflies’ usual overwintering grounds near Mexico City. “We think they came here because people in other places were cutting trees illegally,” says Gregorio Granados Baz, who heads the Communal Land Council. That forced the butterflies to look for a new home.

Habitat loss isn’t the only challenge facing monarchs. They are also suffering from the use of harmful chemical pesticides and a decline in food sources. As a result, monarch populations have dropped by 85 percent over the past two decades. Last year, the International Union for Conservation of Nature classified the North American monarch butterfly as endangered—a species threatened with extinction. So when the butterflies started arriving in Atlautla, the town banded together to protect them by forming the Atlautla Monitoring Brigade.

Vásquez is on the council that manages the Joya Redonda Monarch Butterfly Sanctuary. This 100-acre sanctuary is near the town of San Miguel Atlautla. Fifteen years ago, town residents began noticing large numbers of monarchs on the area’s oyamel fir trees. The butterflies usually spend the winter near Mexico City. Now they were a few hundred kilometers east of that area. Gregorio Granados Baz heads the Communal Land Council. He says, “We think they came here because people in other places were cutting trees illegally.” So the butterflies had to find a new home.

Habitat loss isn’t the only challenge for monarchs. They also suffer from harmful chemical pesticides and a decrease in food sources. As a result, monarch populations have dropped by 85 percent over the past two decades. Last year, the International Union for Conservation of Nature classified the North American monarch butterfly as endangered. The species is threatened with extinction. So when the butterflies came to Atlautla, the people decided to protect them. The town formed the Atlautla Monitoring Brigade.

Monarch butterflies make one of the most remarkable wildlife migrations in the Northern Hemisphere. These amazing insects travel up to 4,000 kilometers (2,500 miles) from their summer breeding grounds in the United States and Canada to reach their wintering grounds in Mexico (see Monarch Migration).

When winter ends, the monarchs fly north, where they lay eggs on milkweed plants (see A Butterfly’s Life Cycle). The leaves of the milkweed plant are the only thing monarch caterpillars eat—and for good reason. Milkweed contains chemicals that make the caterpillars toxic. Some predators have learned to steer clear of them. Even after the caterpillars undergo metamorphosis and transform into butterflies, some of these chemicals remain in the insects’ bodies. A monarch’s bright orange-and-black coloring acts as a warning: “Don’t eat me!”

Monarch butterflies make one of the most remarkable wildlife migrations in the Northern Hemisphere. These amazing insects travel up to 4,000 kilometers (2,500 miles). Their journey starts in their summer breeding grounds in the United States and Canada. It ends in their wintering grounds in Mexico (see Monarch Migration).

When winter ends, the monarchs fly north and lay eggs on milkweed plants (see A Butterfly’s Life Cycle). Monarch caterpillars eat only the leaves of the milkweed plant. And there’s a good reason. Chemicals in milkweed make the caterpillars toxic. Some predators have learned to steer clear of them. The caterpillars will undergo metamorphosis and turn into butterflies. But even then, some of these chemicals remain in their bodies. A monarch’s bright orange-and-black coloring warns: “Don’t eat me!”

Through the spring, multiple generations of monarchs grow from eggs into butterflies. Some members of the new generations continue north, laying eggs along the way. These eggs hatch and turn into butterflies that also lay eggs. In late summer and early fall, the third or fourth generation of monarchs starts to head back south toward Mexico to complete the migration their grandparents or great-grandparents started. On some days of the journey south, they travel more than 40 km (25 mi)! To save energy, they don’t flap their wings much. Whenever possible, they glide on
air currents.

Unlike monarch caterpillars, adult monarchs don’t feed on milkweed leaves. As butterflies, they get their energy by sipping sugary liquid nectar from many types of flowers. While traveling, monarchs stop by flower patches to refuel, just like people on a cross-country road trip might stop at a gas station, says Orley “Chip” Taylor. He’s an ecologist and director of Monarch Watch, a conservation program based at the University of Kansas.

Unfortunately, people are clearing grasslands where milkweed and other flowering plants grow to make room for farms and cities. This has reduced the food available for monarch caterpillars and butterflies during their migration. Recognizing the problem, many people living along monarchs’ migration routes have begun planting butterfly gardens. These contain milkweed the caterpillars need in order to grow in spring and summer, as well as flowering plants to fuel the adults’ flight south in the fall. Even a small pot of milkweed or flowers can make a difference. “Monarchs will find these tiny patches,” says Jennifer Thieme, the science coordinator at Monarch Joint Venture, a conservation organization in Minnesota.

Over the spring, several generations of monarchs grow from eggs into butterflies. Some members of the new generations continue north. They lay eggs along the way. These eggs hatch and turn into butterflies. Then the new butterflies also lay eggs. In late summer and early fall, the third or fourth generation of monarchs starts to head back south toward Mexico. They will complete the migration their grandparents or great-grandparents started. On some days of the journey south, they travel more than 40 km (25 mi)! To save energy, they don’t flap their wings much. They glide on air currents when possible.

Monarch caterpillars feed on milkweed leaves, but adult monarchs do not. As butterflies, they get their energy from sugary liquid nectar. They sip it from many types of flowers. During travel, monarchs stop by flower patches to refuel. It’s just like people might stop at a gas station on a cross-country road trip, says Orley “Chip” Taylor. He’s an ecologist and director of Monarch Watch. This conservation program is based at the University of Kansas.

Milkweed and other flowering plants grow in grasslands. Unfortunately, people are clearing these areas to make room for farms and cities. Now monarch caterpillars and butterflies find less food during their migration. Many people along monarchs’ migration routes recognize the problem. So they’ve begun planting butterfly gardens. These contain milkweed to help the caterpillars grow in spring and summer. They also include flowering plants to fuel the adults’ flight south in the fall. Even a small pot of milkweed or flowers can help. “Monarchs will find these tiny patches,” says Jennifer Thieme. She’s the science coordinator at Monarch Joint Venture, a conservation organization in Minnesota.

Once the butterflies reach Mexico, they rest and feed in the forests. Nestled in the trees, they store up energy for the flight back north in spring. But people have been clearing forested land for ranching and farming. This deforestation has made it more difficult for the insects to find safe havens in Mexico.

The town of Atlautla’s Joya Redonda Monarch Butterfly Sanctuary always had a small group of monarchs visit each year. The majority of the butterflies typically rested west of the country’s capital of Mexico City. But as deforestation continues to shrink that area, the number of butterflies appearing in Atlautla has increased. So community leaders decided to create the Atlautla Monitoring Brigade.

When the butterflies reach Mexico, they rest and feed in the forests. They huddle in the trees and store up energy for the flight north in spring. But people are clearing forests for ranching and farming. This deforestation makes it harder for monarchs to find safe shelter in Mexico.

Each year, a few monarchs always visited the town of Atlautla’s Joya Redonda Monarch Butterfly Sanctuary. Most of the butterflies rested west of Mexico City, the country’s capital. But deforestation continues to shrink that area, and more butterflies are coming to Atlautla. So community leaders created the Atlautla Monitoring Brigade.

Members of the brigade patrol the sanctuary when the insects rest in wintertime, helping to ensure no one disturbs them. Brigade members also lead tours of the sanctuary for people eager to see the massive butterfly colonies. Tour fees help maintain the sanctuary and support the brigade.

Members of the brigade patrol the sanctuary in wintertime, when the insects rest. They help make sure no one disturbs the monarchs. But people want to see the massive butterfly colonies. So brigade members also lead tours of the sanctuary. Tour fees help maintain the sanctuary and support the brigade.