Dr. Leonard Perry, Horticulture Professor
University of Vermont
Butterflies are important pollinators of our food and flower crops. To keep them coming, or if you just enjoy their beauty, provide them with the habitat they need. Butterflies are attracted to landscapes that provide warmth, water, food, and shelter—preferably all near each other.
The first step in creating a butterfly garden is to choose the proper site for them, and preferably one where you can observe them. Butterflies are most active in warmth and bright sunlight, so pick a spot that gets plenty of sun. The air temperature must be at least 40 to 60 degrees (F) for them to become active. Place perches for their sunning in, or near, the garden where butterflies can land and spread their wings. These include flat stones, wooden fence posts, and areas of mulch.
Water for butterflies should be provided in the form of a puddle, not birdbaths, ponds, or large water features. Containers could be a small trench in the soil lined with plastic, a plastic pail buried in the ground, or a dish. Fill the container with sand. Place a few rocks and twigs on the sand to provide landing sites within reach of the water. Then fill the container with water to the level of the sand.
Provide the least hostile environments to butterflies—those least attractive to birds and other predators. One way to keep birds away is with the use of inflatable snakes. Or you can place birdbaths and feeders a distance from the garden. Sticky tape and flytraps will help catch preying insects, as you want to avoid the use of insecticides.
The same products that kill undesirable insects, including electric bug zappers, also kill butterflies and moths. At some stage of their life cycle, all butterflies are susceptible to chemicals, even some of the least toxic ones such as biological Bt products. Some of the feeding damage you’ll see on leaves is probably caused by caterpillars, which you need to tolerate in order to later have butterflies! Usually such feeding is minor, and doesn’t pose a significant nor long term threat to your plants.
A wide variety of plants attract butterflies. Remember that you’ll need to provide food for the larvae, as well as the adult butterflies (mainly flower nectar). Most species are fussy about where they lay their eggs, selecting plants from specific families that will provide appropriate food for hatching caterpillars. Monarch caterpillars only eat milkweeds. Black swallowtail larvae eat leaves of dill, parsley, carrot, and fennel. Painted lady caterpillars eat thistle leaves. In general, caterpillars like weeds such as clover, thistle, and milkweed. If possible, leave a few weeds for them along the edge of the garden or in nearby areas.
Add some vegetables and herbs to encourage butterflies to lay eggs in the garden. Caterpillar forage plants include parsley and ornamental cabbage, which are excellent edging plants for the flower garden. Clover makes a good “living mulch path”. Carrot and dill add fine-textured, attractive foliage to the flower garden.
In general, adult butterflies are attracted to red, orange, yellow, purple, and pink flowers. Also they prefer flowers that are in clusters or flat-topped groupings, and which have short flower tubes. Since they have evolved with flowering native plants, it is important to include these in your landscape. A good listing of native plants, by region or state, can be found from the Lady Bird Johnson Wildflower Center (www.wildflower.org/collections/).
To encourage butterflies to stay all summer long, select plants that flower at different times of the season to provide a continual supply of nectar. Since butterflies are near-sighted, plant more than one of a particular flower to attract them. Butterflies rely on smell more than sight in locating nectar plants, so scent increases the chance of a flower being visited by them. (Their sense of smell is located in their clubbed antennae.)
Planting nectar sources in sites protected from wind helps butterflies fly and forage in the garden with less effort. You could plant windbreaks of trees and shrubs that would provide cover and perhaps even food. Houses, garages, wood fences, and stone walls also serve as windbreaks.
Some butterfly species prefer, even require, overripe fruit to feed upon. Plant some shrubs and trees that produce fruit, such as shadbush, crabapples, blackberries, raspberries, blueberries, and viburnum. Just keep in mind that too many such fruit on the ground also may attract bees, hornets, and wasps.
Since species may overwinter in any of their four stages— egg, larva or caterpillar, chrysalis or pupa (which is the stage that metamorphoses), and the adult butterfly– a variety of winter cover is needed. Butterflies overwintering in the adult stage may use the peeling bark on trees, perennial plants, and old logs or fences. Old sheds, barns, or houses also provide overwintering sites. Similar sites are used by overwintering pupae. Butterfly hibernation boxes are seldom used by them, but more frequently by wasp colonies.
Butterflies overwintering as caterpillars or eggs use herbaceous perennials, shrubs, and trees. Leave the leaf litter and dead plant parts of perennials in the garden until spring to provide cover for them from predators such as birds.
You can learn more about butterfly gardens, and how to officially certify yours, from the North American Butterfly Association (nababutterfly.com/).
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