Create a Butterfly Garden To Counter Habitat Loss

The eastern monarch butterflies seen on the East End of Long Island in spring and summer begin their migration to the mountaintops of Central Mexico in late August. There, the World Wildlife Fund records the population annually.

The latest data is alarming: The population is down 59.3 percent compared to the previous winter, and it’s the second-lowest it has been in three decades of record-keeping.

The Monarch Joint Venture, a national partnership of U.S. state and federal agencies, nonprofits, businesses and academic programs, attributes the monarch decline in North America primarily to loss of habitat, a threat compounded by indiscriminate use of pesticides and climate change.

Though the problem spans the continent, individual gardeners have the power to be part of the solution. Starting a butterfly garden creates a refuge and breeding ground for monarchs, as well as other butterfly species and pollinators at large.

Master Gardener and garden coach Mary Vienneau, the proprietor of garden design business Mary’s Garden, has for the past few years been replacing the front lawn of her East Quogue home with butterfly habitat — and enjoying the beauty of the gardens and the wildlife that the habitat has attracted.

“It’s just great not to have lawn,” Vienneau said during a March visit to her home. “Lawn is just a waste of space, in my opinion.”

She started her first butterfly garden in 2018. First, she laid cardboard over the turf grass between her circular driveway and the road and let it sit for about three months. Then she topped the cardboard with compost and was ready to plant into the garden within three to four months.

A butterfly garden needs two kinds of plants: nectar sources and host plants. Flowering plants provide nectar to give butterflies energy. Host plants are where butterflies lay their eggs, and those eggs hatch into caterpillars that eat the leaves and buds of the host plants.

“The only host plant for monarchs is milkweed, period,” Vienneau said. “That’s it.”

Milkweeds are plants that belong to the genus Asclepias. They contain toxic substances known as cardenolides. When monarch caterpillars eat milkweed, it doesn’t harm them — and they themselves become unpalatable to potential predators.

A monarch egg hatches in five days, give or take a day, and the caterpillar that emerges spends the next 10 to 14 days eating milkweed before reaching full size, at which point it crawls away as far as 30 feet to pupate, forming a jade chrysalis.

There are many species of milkweed, though Vienneau only uses those that are native to the region.

“I don’t recommend using tropical milkweed,” she said. “It’s not native. It grows like wild in Texas and Florida. We don’t need that here. We want just the milkweed that grows here.”

In another 10 to 14 days, a butterfly emerges from the chrysalis and seeks nectar sources.

Vienneau’s garden offers a veritable buffet.

“Every year, I add more and more to it,” she said while standing in her original butterfly garden. “I’ve got Sedum. I have Phloxes. I have Monarda — they love Monarda. These are all nectar plants.”

Monarda is a genus that goes by the common names bergamot and beebalm. She also touts Echinacea, or coneflower, as a great nectar plant.

The garden also includes a border of Chrysanthemums that serve as a late fall nectar source after many others flowers are spent. In early March, her irises were already blooming, and crocuses and snowdrops are peeking out from the soil.

“I get my first flowers now in March, and then I’ll have flowers until November — and that’s the key,” Vienneau said. “… You could have monarchs migrating in November, so you want to have food for them.”

She also grows primrose, which stays in flower all winter, and she continues to increase the number of flowers in her garden both in terms of volume and variety.

“My husband always says, ‘The great thing about Mary’s garden is every year, it changes,’” she said. “We add to it, add to it, add to it.”

She created another butterfly garden bed three years ago — there is now an old boat in the middle of the bed, full of soil that’s been seeded with milkweed — and she wants to start a third soon, further reducing her lawn.

Vienneau said having to cut a lawn every week with a gas-powered machine to keep it green is ridiculous. Meanwhile, her garden is beautiful until the first hard frost, she said.

She doesn’t cut down her garden in fall after frost kills the herbaceous plants. She explained that insects hibernate in the hollow stems of these plants over the winter, and the seed pods are food for birds. “The birds have been eating the seeds in here all winter,” she said.

Once she sees the first bee of spring, she knows it’s time to clean up, though she leaves some leaves behind and top-dresses the garden with compost.

“You can leave the leaves, and they will decompose underneath the compost,” she noted. Gesturing to a leaf-covered garden bed, she said, “Under there is just teeming with life.”

Insects, including bees and other pollinators, overwinter in and under leaf litter, though her clients typically object to having any leaf litter around. “They want it clean and neat, and not one leaf left on the property,” Vienneau said.

“You know, it’s hard to educate people just to let it be — leave the leaves. You don’t have to remove them. They can stay. You can move them in the spring.”

Spring seems to be coming earlier and earlier. Vienneau observed some March flowers that appeared in her garden earlier than they normally do, and she noted that parts of the East End have moved into a warmer zone on the U.S. Department of Agriculture plant hardiness zone map. “They just updated it,” she said. “We used to be 7a. Now we’re 7b. So climate change is definitely real.”

Reveling in Nature

Vienneau found herself out in her butterfly garden with a cup of coffee observing the insects so often, she added a bench to sit on. “It’s like a little show,” she said. “It’s entertainment for me.”

Milkweed will attract a wide variety of insects, including aphids and milkweed beetles that will eat the plants themselves, and bees and other pollinators that come for the nectar and pollen in the flowers. Milkweed is also the host plant for the milkweed tussock moth, with caterpillars that are fuzzy, like yarn, in black, white and orange.

All sorts of wasps, bees and butterflies, as well as ladybugs and other beetles, visit for the nectar and pollen, or to prey on other insects. “I’ve even seen spiders come and kill a wasp and having major battles in my garden,” Vienneau said.

The wasps are not the stinging kind that gardeners don’t like to have around. These wasps pollinate, and many are predatory or parasitoid species that keep the populations of aphids and other pest insects under control.

Vienneau also sees many dragonflies, which she attributes to having a pond.

“Having a water source is very important. I have a pond in the back, so that’s a great place for everybody to get a drink of water, because they all need water, too. So you should have bird baths and fresh water for them.”

Choosing and Maintaining Milkweed

Common milkweed (Asclepias syriaca) has pompom-shaped pink flowers that bees love. While a native, common milkweed also is an aggressive spreader, colonizing gardens via rhizomes.

Vienneau does not recommend common milkweed for small gardens, because its hard to eliminate from areas where it is unwanted.

“I always suggest that to people who have a field,” she said. “... I regret putting it in these two gardens because it’s going through my driveway now.”

Other native milkweed varieties, such as butterfly weed (Asclepias tuberosa), grow in clumps. They don’t live as long — maybe a four-to-five-year lifespan — but are easy to propagate by saving the seeds, she explained.

“You put the seeds down, actually, when it’s winter, and then they sprout in the spring,” she said. “So you can have plenty of milkweed. I don’t spend any money on milkweed now. I just replenish with the seeds that I have.”

She said starting from seed can take three years to get blooms. “You have to be patient, unless you buy the plants,” she said.

Vienneau recommends Fowler’s Garden Center in Southampton, which has a native plant selection.

According to the University of Minnesota Monarch Lab, each monarch caterpillar needs one mature milkweed plant to eat enough to reach maturity. So the denser a butterfly garden is with milkweed, the better.

“There are a lot of pests that will live on the Asclepias, so I put coffee grinds at the base of all my milkweed, and that keeps the aphids off,” Vienneau said. “That’s probably the biggest problem, aphids, and they can make the milkweed look messy.”

Host Swallowtails, Too

While monarch butterflies are seasonal guests, the other common large butterflies on the East End, the swallowtails, are residents. They overwinter here in their pupal stage and will emerge once the temperature and day length have increased.

There are hundreds of swallowtail species, but the three most likely to be found in the wild on Long island are the eastern tiger swallowtail, the black swallowtail and the spicebush swallowtail.

Black swallowtail host plants are the umbellifers. These include carrots, Queen Anne’s lace, parsnip, celery, parsley, cilantro, dill, fennel and more. “Anything in that family, they will lay their eggs on and eat,” Vienneau said.

At all of the properties where she designs gardens, she endeavors to include lots of parsley for the swallowtails.

Once a customer sent her a picture of swallowtail caterpillars on parsley, asking what they were. The customer planned to spray the caterpillars with pesticide and wanted to know if it was a good choice.

Vienneau told her not to do anything, ran over and collected the caterpillars. She brought them home and reared them until they became butterflies, just like she rears monarchs.

She has parsley growing at her home garden, too, plus various other herbs around borders and walkways. “It’s a really pretty, and it’s green almost all winter,” she said. “It’s a really pretty little plant, and you can use it all winter.”

Eastern tiger swallowtail host plants include tulip trees, wild black cherry, ash, birch, and sweet bay Magnolia. Spicebush swallowtails also use tulip trees in addition to sassafras and its namesake spicebush.

There are many other butterfly species native to the East End that aren’t quite as big, colorful and noticeable as monarchs and swallowtails that will benefit from a butterfly garden, and countless other insect species that aren’t as charismatic as butterflies, but are important food sources for songbirds and other wildlife that could use a hand in the face of habitat loss.