Plant some milkweed in your yard this year — and you can help save the monarch butterfly.
Monarch butterflies, well-known for their unique migration from across the United States down to Mexico each fall, have been in decline for years and are at the lowest numbers scientists have seen in the several decades they have been tracking them.
The easily identifiable orange-and-black monarchs have been hit hard by a number of factors, but perhaps most devastating is the loss of the one species of plant the monarch lays its eggs on — milkweed.
As a result, the Audubon Society is asking residents to plant milkweed in their gardens and for highway road crews and parks groundskeepers to avoid cutting milkweed that grows wild along roads and in open spaces. Bergen Audubon is also donating milkweed plants to schools and community gardens.
"We're trying to do what we can to help," said Don Torino, Bergen Audubon's president. "Some environmental issues seem so big and overwhelming, and people feel powerless. But here's something simple they can do to help."
Milkweed is essential to monarchs because it is the only plant that the butterfly species lays eggs on — and which the monarch caterpillar can eat.
Monarchs migrate south each fall to fir forests in the mountains of central Mexico, where they spend the winter. In the spring, they migrate north and spread throughout the United States.
The generation that spends the winter in Mexico can make it back north as far as Texas, and lay its eggs on milkweed plants. Within four days, the eggs hatch into yellow-white-and-black-striped caterpillars, which eat the host plant's leaves. After two weeks, the caterpillar attaches to the underside of a branch or leaf and becomes a chrysalis. Ten days later, after metamorphosis, the full-grown monarch emerges and continues the migration north. Monarchs will go through four generations of butterflies during the spring and summer migration process.
But several factors, incluidng illegal logging and extreme weather, have disrupted the traditional migration and reduced the monarch numbers.
But perhaps the most significant factor has been the loss of milkweed plants as large-scale commercialized farms have used herbicide around fields. The herbicide kills weeds around the farmland — including wildflowers and milkweed. Without milkweed, the monarchs have no place to lay eggs, and their caterpillars have no food source.
In addition, during the migration season, monarchs rely on milkweed and other wildflowers for the nectar to help fuel their journey. Herbicides have also knocked out swaths of wildflowers, cutting the monarchs' nectar supply.
The common milkweed, which grows in empty lots and along roads and fields, "is not very attractive — it grows to 3 feet and looks very weedy and has big leaves. It tends to get cut down," said Janice Mahr, who grows perennials for Metropolitan Plant and Flower Exchange in New Jersey.
Most nurseries carry two types of milkweed that have been cultivated to look better in gardens, she said. The cultivated versions are asclepias tuberose, or butterfly weed, which has round masses of tiny bright orange flowers, and asclepias incarnata, or swamp milkweed, which comes with white or pink flowers.