During a recent Monarch butterfly tagging program at the Mercer County Library System in Lawrence, a young girl watched as a butterfly lifted from her hand and flew into the garden.
“This is the best day of my life,” she told her mother.
For Christine Crawford, youth services director at the library, moments like that are the most rewarding part of the program.
Tagging the butterflies involves holding them carefully and affixing a tiny alphanumeric sticker to the underside of one wing.
According to Monarch Watch, the organization that supplies the tags and keeps track of the data, “Tagging helps answer questions about the origins of monarchs that reach Mexico, the timing and pace of the migration, mortality during the migration, and changes in geographic distribution.”
Across Mercer County, libraries are becoming unlikely hubs for monarch butterfly conservation. At the Lawrence branch of the Mercer County Library System, staff and volunteers raise and tag monarch butterflies as part of a national migration tracking program while also building native pollinator gardens designed to support the declining species.
The effort, which began with a handful of milkweed plants outside the Lawrence library, is now expanding.
In the fall of 2021, Sharon Wang, adult programming librarian at MCLS, started the butterfly garden in front of the library with a few milkweed plants from her personal garden. In the spring of 2022, the Monarch Tag and Release program began.
Since that time, Kelly Rypkema, director of environmental education at Mercer County, brought another 1,500 native plants and grasses to MCLS.
The plants were chosen to be sustainable, lower maintenance, pollinator- and bird-friendly, and able to provide blossoms throughout three seasons of growth. Library staff and volunteers helped install them.
Wang says the reason for starting this program at MCLS is that the butterflies are a vulnerable species that makes them “a natural focus for our educational programming at the library.”
She added, “Although the Monarch is the main focus of the program, Black Swallowtail, New Jersey’s state butterfly, became part of the program as an opportunity to highlight another meaningful native species.”
Some conservation groups caution that captive rearing of butterflies should be done carefully. The Xerces Society for Invertebrate Conservation notes that raising monarchs in captivity can “increase parasites that may spread to wild populations” and, when done repeatedly over multiple generations, may reduce genetic diversity.
At the same time, conservation organizations say restoring native habitat is one of the most effective ways communities can support monarch butterflies. The Monarch Joint Venture encourages planting milkweed and other native pollinator plants like those in the library gardens.
Because of its success, the butterfly garden at the Lawrence Library has become the model for other libraries in Mercer County to follow.
Rypkema has installed a native plant garden at the library branch in Hopewell and is in discussions with the Ewing, West Windsor, and Hickory Corner branches to do the same.
Mercer County Executive Dan Benson, along with the Mercer County Planning Department, has approved using funds from the county’s open space trust fund to cover the cost of the native plant garden effort in recognition of this need, Rypkema says.
Rypkema said: “This was the first of a series of a grassroots initiative for native plant gardens that the County Executive gave me permission to install. As a first step, we’re starting with some of the county libraries because they’re community hubs, and it seemed to make a lot of sense to start there.”
How milkweed helps monarch butterflies
Milkweed plays a critical role in the monarch butterfly’s life cycle. Monarch caterpillars feed exclusively on milkweed leaves, making the plant essential for the species to reproduce and survive, according to the National Wildlife Federation.
Adult monarchs lay their eggs on milkweed plants. When the eggs hatch, the caterpillars rely on the leaves as their only food source before forming a chrysalis and eventually emerging as butterflies, according to the U.S. Fish and Wildlife Service.
Because milkweed has declined across much of North America due to development, herbicide use, and changes in land management, conservation groups encourage individuals and communities to plant native milkweed varieties to help support monarch populations, according to the Monarch Joint Venture, a national monarch conservation partnership.
At the Mercer County Library System’s Lawrence branch, milkweed is one of the key plants growing in the butterfly garden used for the monarch tagging program.
Library staff also distribute milkweed seed packets to visitors at the end of tagging events so families can plant their own pollinator-friendly gardens at home.
Planting milkweed and other native flowering plants can provide food and habitat not only for monarchs, but also for bees and other pollinators that play an important role in local ecosystems, according to the National Wildlife Federation.
