SOUTHWEST HARBOR, Maine — The butterflies were roosting on a recent foggy morning in Charlotte Rhoades Park and Butterfly Garden. Wings shut, they clung to the undersides of leaves and colorful blossoms, waiting in shelter for the sun.

“Their bodies need to be warm in order for them to function — and functioning is nectaring, mating, laying eggs, flying around,” said Ann Judd, master gardener and volunteer at the butterfly garden since it first opened in 1998 on Main Street in Southwest Harbor.

Judd knows her butterflies, and she shared her knowledge with attendees of the garden’s annual butterfly release on Thursday, when volunteers passed out containers holding painted lady butterflies. The crowd gathered in the flower-filled garden, opened their containers, and set the butterflies free.

As the garden’s only major fundraising event, the butterfly release “keeps the garden going,” Judd said. Located in a town-owned park, the popular garden is maintained by volunteers, and the money they receive from the fundraising event and the donation box at the garden parking lot is spent on supplies and projects to improve the look and function of the garden.

“Butterflies are going to be attracted to not only the color but the fragrance,” Judd said as she walked through the garden, pointing out a wide variety of annual and perennial flowers, vegetables and blossoming trees.

“They see in the ultraviolet range,” Judd added. “Their favorite colors are blue and purple.”

A brochure available at a kiosk at the park’s parking area lists different Maine butterfly species, as well as the types of plants that attract them and why. Black swallowtails, white admirals, clouded sulphurs and meadow fritillary — these are just a few of the many butterfly species found in the Southwest Harbor garden.

At the butterfly release, volunteer docents were stationed throughout the garden to tell people about the butterflies and the plants that they require to survive. They pointed out butterfly eggs, caterpillars, chrysalises and the adult butterflies themselves.

“Once you know what to look for, it’s easy to find,” Judd said, pointing out the tiny egg of a monarch butterfly on the underside of a swamp milkweed plant.

A Monarch Tent was also part of the butterfly release event. In the tent, garden volunteers showed off these beautiful orange, black and white butterflies, and discussed their amazing migration story from Mexico to Maine. They also showed how the garden is tagging monarchs to track their movements.

“There is a little sticker that’s about the size of the end of my finger, and you actually place it on the monarch’s underwing, on a discal cell, one of the cells of the wing that doesn’t interfere with their flight,” Judd said.

On July 19, Judd had several monarch chrysalis in a containers at the garden. The pale green sacks, spotted with gold flecks, contained butterflies transforming from caterpillar to winged adult.

Monarch butterflies, a species in danger of disappearing from Maine entirely, migrated to the Southwest Harbor butterfly garden this spring for the first time in eight years.

“I can’t tell you what a celebration that was,” Judd said. “It was so, so exciting.”

The migrating monarch butterfly population in Maine has declined about 95 percent over the past 20 years, Judd said, and this downturn is happening for a number of reasons, including illegal deforestation of their wintering grounds in Mexico, the use of pesticides along their migration path in the United States, and the destruction of their food source: milkweed.

Monarch caterpillars only eat milkweed, a plant that is toxic to most animals. This means the monarch has little competition for food, but its fate is also closely tied to the milkweed plant.

In the Charlotte Rhoades Butterfly Garden, many different species of milkweed are planted to attract and feed monarchs, including common milkweed, swamp milkweed and butterfly weed. And it appears their efforts have paid off. The monarch is thriving in the garden this year. In every milkweed patch, you can find monarch caterpillars at various stages of growth, gnawing at the foliage, and under the leaves you’ll find tiny monarch eggs and chrysalises, green sacks flecked with gold from which the caterpillar transforms into a winged adult.

“Each of these butterflies has its own very interesting story,” Judd said.

The mourning cloak butterfly lives year-round in Maine as an adult, she said as an example. It survives the harsh winter by taking shelter and hibernating. And in the early spring, on warm days in March, they emerge and fly about, drinking tree sap for nourishment.

Because butterfly species vary so much in their life cycles and habits, there was much to take into account in creating a butterfly garden, Judd said. Each butterfly has different host plants, which can be broken down into larval plants, which the caterpillars eat, and nectaring plants, which the adult butterflies draw nectar from.

The resulting garden is one of many colors, shapes and scents, pleasing to people and butterflies alike. And while few visitors realize this, if the garden is seen from the sky, the flowerbeds are arranged in the shape of a butterfly, designed by Maine landscape architect Bruce Riddell.

The property where the garden is located was left to the town in 1972, to be used as a park and quiet place for children to play. Over the years, the lawn grew up into shrubs and lupines, making the property unwalkable, Judd recalled.

Judd was one of several community members who worked with local children to transform the space into a butterfly garden and lawn in 1998, a project that won an award for park planning and community process from the Boston Society of Landscape Architects.

The garden opened with a celebratory butterfly release. Ever since, garden volunteers have continued to organize a release each year as a fundraiser. Usually between 150 and 200 people participate in the event, for which advance registration is required. Admission is $30 for ages 12 and older and includes a butterfly. Children under the age of 12 get in for free, but they must share a butterfly with an adult.

“We have a lot of children here, so it’s kind of like a Norman Rockwell picnic,” Judd said.

Aislinn Sarnacki

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...