FEEDING YOUR BUTTERFLIES
Dr. Leonard P. Perry, Extension Professor
In order to attract and keep butterflies in your landscape, you need to create the proper habitat. As with any living creatures, a main part of this is food. So what do butterflies eat? Some general suggestions on types of plants, as well as specific plants, can be found in Bulletin 7151 from the University of Maine.
Butterflies have four life stages, two of which have needs for food-- the larvae or caterpillars, and the adults or butterflies. The larvae of many butterflies aren't particular, but some are. For instance, monarch larvae only eat milkweeds. Black swallowtail larvae eat the leaves of dill, parsley, carrot, and fennel. Painted lady larvae eat thistle leaves. You must provide food for such larvae, or you wont have the adults!
Other herbaceous plants that provide food for larvae include wormwood,
hollyhock and other mallow relatives, cabbage and related cole crops, sunflower,
alfalfa, and clover. Some shrubs for feeding larvae include privet,
lilac, and some viburnums. Many trees provide larval food including
some species of shadbush, birch, hornbeam, hackberry, ash, poplar, oak,
sumac, willow, and elms.
Nectar provides food for the adult butterflies. In addition to sugar and water, it provides other nutrients such as amino acids, proteins, enzymes, and vitamins. Once the nectar is gone, the butterflies will move elsewhere. So provide a steady supply through annual flowers, or a succession of flowering perennials and woody plants.
Early season nectar sources are important for butterflies that overwinter as adults. Examples are lupines, dames rocket, and lilacs. Late season nectar sources are important for species that end the season as adults. Asters, goldenrod, helen's flower, and butterfly bush are examples. Butterfly bush may not be winter hardy in the colder areas, in which it may either die to the ground in winter, or just be grown as an annual. Because late fall flowers have less nectar than those that bloom earlier, fall-feeding butterflies need to visit more flowers to satisfy their nutritional needs.
Many nectar plants also provide cover for butterflies. Some are also larval food plants, so additionally provide egg-laying sites.
Butterflies have a proboscis-- a straw-like mouthpart they use to acquire nectar, as well as to drink from puddles. The length varies with species, so determines which flowers a particular butterfly will visit. When choosing nectar plants, choose ones with nectaries accessible to the butterfly's proboscis. Smaller butterflies cannot reach the nectar in deep flowers. Many double flowers not only have less nectar than single flowers, but also make access much more difficult.
Use a diversity of plant species. This will accommodate the flower size and plant species requirements of a number of different butterflies.
Plants with flower clusters, such as milkweed, joe-pye weed, showy stonecrop, and garden phlox give a place to land and are big enough to support large butterflies. Composite flowers such as blazing star, black-eyed susan, purple coneflower, goldenrod, zinnia, and aster also provide a landing place.
The size of the flower doesn't influence the quality nor quantity of nectar. Many herb plants have small flowers, yet are excellent nectar plants. Some flowers even have nectar guides-- a different color in the center of the flower that the butterflies can see, even if we can't.
Plants receiving sun at least six hours a day have more nectar than plants receiving less. Fertile soil is important for healthy plants, and healthy plants produce more nectar.
Butterflies are near-sighted, so large masses of flowers attract them. Plant many types, or many of the same type of flower in a grouping. One way to increase the number of flowers, and to extend the bloom season, is to pinch back the stems early in the season.
Butterflies rely on smell more than sight in locating nectar plants. Their sense of smell is located in their clubbed antennae. Scent increases the chance of a flower being visited by butterflies, and so of being pollinated. Once pollinated, the flower loses the scent that attracts pollinators. Its energy then goes into the development of the seed and fruit, instead of into the production of nectar.
Lastly, plant shrubs and trees that produce fruit. Some butterfly species prefer, even require, overripe fruit to feed upon. Examples are some shadbush, crabapples, blackberries, raspberries, blueberries, and viburnum. Just keep in mind that too many such fruit on the ground may also attract wildlife in the form of bees, hornets, and wasps.