Via ecoRI News (ecori.org)

WAKEFIELD, R.I. — Planting milkweed in your garden may save a Mexican forest. Migrating monarch butterflies rely on milkweed plants for cover and nutrition on their annual 2,500-mile migration from the oyamel fir forests along Central Mexico’s Transverse Neovolcanic Mountain range to the United States and Canada.

In their larval stage as caterpillars, milkweed is all they consume, but a host of causes have limited areas for the species to grow. Planting milkweed is a simple and beautiful way to bring life, color and sustenance to our yards, and Blue Moon Farm, on Saugatucket Road, has quietly become one of Rhode Island's largest providers.

In their larval stage, monarch butterflies are caterpillars.

Monarch butterflies are miracles of strength and persistence, with simple needs for a brief nine-month life. For protection from dangerous elements of cold and rain, they crowd by the thousands on sagging branches of Mexico’s sacred fir trees. This forest once covered greater expanses, but a warming climate forced it up mountainsides into cool, moist air, and with them went the butterflies.

Monarchs overwinter in just 12 locations there, sheltered from extremes amongst the needles and under protective cloud cover, where cool temperatures lower their metabolic rate, conserving expenditures of lipids, necessary to fuel their journey north come springtime. Before leaving, monarchs mate to begin their cycle of new life.

It was because she is so interested in native plants that Jane Case, owner of Blue Moon Farm, began her business designing and creating perennial gardens more than 30 years ago. It was her understanding of how beneficial milkweed is for butterflies and other winged animals, combined with her artist’s eye for bringing special colors to gardens, that convinced her to originally offer a few varieties. Customers were slow to the idea of planting “a weed” in their private spaces, but recently, as the monarch’s plight has gained widespread attention, sales have increased.

“This has been a long haul,” Case said with a laugh.

It takes four generations to complete a monarch migration. Throughout the route, females will deposit up to 500 milky-white eggs the size of a pen tip on the underside of milkweed. In a week or less, the eggs will hatch, allowing emerging caterpillars to feed on the leaves and their nutritionally rich latex sap. The sap also contains toxic glycosides, which stores in their exoskeletons and, later, their wings, causing them no harm but sickens any who prey on them. Combined with their vivid, striking colors, the toxin serves as an effective warning system.

In just over a month, monarchs transform from those tiny eggs to larval caterpillars, to pupa encased in a silken chrysalis to adult butterflies. Throughout this cycle, it’s milkweed which feeds and protects them.

In about a month, monarchs transform from tiny eggs to larval caterpillars, to pupa encased in a silken chrysalis to adult butterflies.

Larvae seem to feed solely on milkweeds in the genus Asclepias, named in honor of the Greek god of medicine and healing, Asklepios. In their larval stage, they rely mainly on butterfly weed, swamp milkweed or common milkweed.

In turn, the 76 milkweed species depend on butterflies, bees, ants, moths and wasps to transport pollen from their pollinarium to the receptive stigma on other flowering plants. This reliance means more beneficial creatures in gardens, with the bonus of being deer deterrents.

Blue Moon Farm sells five species of Asclepias, including varieties of incarnata such as Cinderella, ice ballet and milkmaid. Because milkweed are perennial, living for more than one year and reproducing from rootstock in addition to seeds, they’re a natural fit in her 3-acre nursery, Commercial gardeners from all over the state have become Case’s largest milkweed clients.

In front of the retail store, Case and the farm’s manager, Mike Yarworth, have planted the tropical milkweed curassavica, so customers can see how beautiful the flowers are and how they aid in the butterfly’s metamorphosis.

“Our goal is to encourage monarchs to lay eggs on the leaves, to feed, to form a chrysalis and watch the whole cycle,” Yarworth said. “We want to see the butterfly emerge.”

He and Case have also observed monarchs favoring the tropical milkweed, which tend not to propagate the following spring so are better choices for smaller gardens.

As researchers learn more about monarch migrations, they have found a significant loss of habitat, from fields containing milkweed tilled over to grow more valuable hays for animal feed, persistent urban sprawl, and liberal use of chemical herbicides, sprayed to kill whatever is undesired, especially plants whose name includes the word “weed.”

To compound this loss of habitat, native Mexican peoples continue to harvest fir for fuel, religious ceremonies and profit.

Monarchs butterflies begin to leave Canada and northern New England from August through late December, as milkweed produces long pointed pods full of seeds tailed with silken white fluff, ingenious parachutes designed to carry them on fall breezes. It’s a natural magic, a genetic gift, that leads these fourth-generation butterflies home to Mexico and the cool mountainous forests of sacred oyamel firs to rest and mate.

Blue Moon Farm sells varieties of milkweed that protect and feed monarchs on their magnificent migrations, and, when year classes are strong, greater populations will return to Mexico — their gorgeous millions dabbed black and orange will crowd on branches, reserving their energy for new journeys north.

Those increased populations will serve as vivid reminders of just how critical it is to preserve and protect the sacred fir forests.

Rhode Island resident Todd Corayer runs a blog called "the fishwrap writer''.