Milwaukee Public Museum

by Susan Borkin

EDITOR'S NOTE: This article is reprinted from LORE magazine (vol. 43, no. 2 (June, 1993), p. 12-15), a benefit of museum membership. ©1996 Milwaukee Public Museum, Inc.

In 1883, the first catalogue of Wisconsin's butterflies was published by Philo Romayne Hoy, a country physician and one of the state's early naturalists. Sixty-eight butterfly and thirty-one skipper species were reported, nearly all collected within ten miles of Racine. A few of the butterflies considered to be common by Hoy, such as the zebra swallowtail, now only rarely wander into the state from breeding grounds to the south. But most of the species he reported can still be found here, if you know where to look for them, along with species that have been added to the list. Still, the abundance of these interesting animals has declined drastically since Hoy's time. The destruction of natural habitats, including elimination of "weeds" and native grasses from yards, parkways, roadsides, etc., along with misuse of pesticides has contributed significantly to their demise.

Most people recognize the monarch butterfly, and vegetable gardeners are usually familiar with the cabbage butterfly which lays its eggs on broccoli and other plants in the mustard family. But beyond these two, the average person is hard pressed to name any of the other butterflies found in Wisconsin. Fortunately, this situation can be remedied in a fascinating manner. One solution is to create your own butterfly garden. The first step is to obtain one of the field guides to butterflies, such as the Golden Nature Guide. These guides provide information on the type of habitat each species prefers, what the food plants of the caterpillars are, and when the adults are on the wing, in addition to identification aids. Obviously, a butterfly like the bog copper, which is found only in acid bogs and lays its eggs on cranberry plants, is not a likely candidate for the urban or suburban yard. An assessment of the types of habitats that your yard provides, whether it is sunny or shaded, and what habitats are found in the surrounding neighborhood will be the first clue to which butterflies are potential visitors.

Butterflies have a rather complex life cycle in that development occurs by a process know as metamorphosis. Life begins as a tiny egg that in most cases is securely glued to a plant that a fertilized female has selected with discriminating taste. Usually within a week to ten days, a small caterpillar will chew its way out of the egg case. For each species of butterfly, the caterpillar stage has its own specialized requirements for growth and will feed only on plants that its species has evolved an ability to process. As the caterpillar grows, it molts or sheds its skin about five times, often changing color and markings. The final molt transforms the caterpillar into a chrysalid (also called a pupa). No feeding occurs in this stage. Rather, energy stored up by the caterpillar is used to reorganize and build new body tissues. When this stage of development has been completed, the adult butterfly emerges leaving behind an empty chrysalid shell. Emergence times vary with species, in general being will synchronized with the season and availability of resources needed by each.

A butterfly garden that combines food plants for caterpillars with a variety of nectar-rich plants and other attractants for adults will be the most successful. Food choices are less restrictive for adult butterflies than for the caterpillar stages, but adult butterflies have specific nutritional requirements as well. Water, minerals, proteins, fats and carbohydrates are utilized for body maintenance, production of eggs and the like. Nectar, carrion, animal excrement, rotting fruit, and tree sap are all important food sources for various butterflies. Specific needs may vary between species and for individuals of the same species over time. For example, the question mark butterfly produces several generations during the growing season but only the last brood of adults hibernates through the winter. They must rely on the store of nutrients within their bodies to carry them until spring, a rigor that individuals produced early do not have to contend with.

The long tube-like mouth of a butterfly, called a proboscis, is adapted for feeding on liquids. When not in use, the proboscis is tightly coiled under the butterfly's head. You may recall having seen male butterflies congregating at a damp spot along an unpaved road. This behavior is referred to as "puddling." Fluid sucked up the proboscis is pumped through the insect's body to extract dissolved salts and minerals which may be incorporated into pheromones or scents released by the male during courtship. A small water hole can easily be added to the garden. Select an open spot, perhaps alongside a path, and bury a bucket int he ground. Pour sand to within an inch of the top, then fill the bucket with water and add a few sticks or stones. Voila, instant puddle.

An aesthetically pleasing garden that provides a continual array of color can be achieved by taking into consideration the growth form, height, blooming period and other characteristics of the plants you select or allow to grow naturally.

Buddleia, or butterfly bush, is a plant that butterflies find especially alluring. At times, I've seen individuals of three or four different species imbibing together at this plant. It grows to a height of four to six feet, has slender silvery leaves, and blossoms with multiple florets, similar to lilacs. Colors range from white to deep rose, pink, lavender, and blue. In Wisconsin, the plant dies back to ground level during winter and sends up succulent new growth in the spring. Another butterfly favorite is the orange milkweed, Asclepias tuberosa, also know as butterfly weed. A native plant, it does best in sandy well-drained soil and full sun.

A benefit, in addition to the beauty of the garden and pleasure of watching its visitors, is the opportunity to observe, to wonder, and perhaps to gain some insight into the workings of the natural world. The ways that butterflies colonize new resources, their associations with specific plants, the checks and balances provided by predators and parasites are but a few of the dynamics that can be examined within the butterfly garden.