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Contacts:
Donald Lewis, Extension Entomology, (515) 294-1101, drlewis@iastate.edu
Elaine Edwards, Extension Communication Systems, (515) 294-5168, eedwards@iastate.edu

Yard and Garden Column for week beginning Jan. 5

Plan Ahead for Butterflies

By Donald Lewis
Extension Entomologist
Iowa State University Extension

The garden catalogs have started to arrive in our snow-covered mailboxes so it must be time to start planning for next summer's gardens. How about making plans to encourage butterflies in your garden? If you have been reading the news about pesticides and genetically modified crops, you might believe butterflies need all the help they can get. Why not give them a break in your own backyard?

Butterflies and flower gardens seem to naturally go together, but creating a garden or landscape designed to attract and maintain butterflies takes some special planning and effort. Fortunately, a garden for butterflies is not radically different from what you already have. In fact for most gardeners, a small sign that says, "butterflies welcome" would turn your existing flowerbeds into a legitimate butterfly garden!

"Butterfly gardening" is flower gardening that gives special consideration to the needs and requirements of butterflies. There are two main purposes to butterfly gardening. First, some gardeners are simply interested in watching butterflies lured into the garden to feed on flower nectar. With careful planning you can increase your chances of having butterfly visitors by diversifying your landscape and creating a garden with a wide variety of plants providing continuous bloom of nectar-producing flowers throughout the summer.

The second challenge of butterfly gardening is to plan and plant the landscape for the purpose of raising butterflies from caterpillars. Like the flies, beetles and moths, butterflies have a complete life cycle with four stages: egg, larva, pupa, and adult. A butterfly larva is more commonly referred to as a caterpillar and the pupa is called a chrysalis (plural is chrysalids).

Raising butterflies from caterpillars in your garden often requires a major change in attitude. Caterpillars have chewing mouthparts and they must eat plant foliage as their food source. Hungry caterpillars can consume a surprisingly large amount of foliage, and butterfly gardening requires that you stand back while "worms" are eating your plants. Such tolerance is not for everyone. The initial reaction of many gardeners is to call any caterpillar a "pest" and eliminate it as soon as possible!

Caterpillars feed on foliage of trees, shrubs, flowers, vegetables and weeds. Some kinds of caterpillars are picky eaters that will eat only one kind of plant. The well-known monarch butterfly, for example, only grows where milkweeds are available. Other caterpillars can survive and grow on any of several different host plants. For example, the caterpillar of the attractive tiger swallowtail can be found on the foliage of cherry, ash, birch, cottonwood, willow or lilac.

Resources

Raising butterflies in your garden requires you to learn which plants are necessary for the caterpillars of butterflies common in your area. Iowa State University Extension pamphlet PM 1795, "Common Butterflies of Iowa," provides a color photograph of our most popular butterflies and a brief description of their biology, habits and host plants. Contact your local county extension office to obtain a copy for only $1.00. Other butterfly field guides, general gardening and butterfly gardening texts are available at libraries, bookstores and garden centers. Finally, a free, printed list of common Iowa butterflies and their food plants will be mailed to you upon request to Extension Entomology Office, Iowa State University, Ames, IA 50011 or e-mail to insects@iastate.edu

A butterfly garden can be as small as a window box or as large as a field. However, specific characteristics about the site will improve your chances of success. First, the garden must be in a sunny location. Butterflies are predominately active when it is warm, bright and sunny, and most of the plants used in butterfly gardens grow best in full sun. An exposed, windy location discourages butterflies so provide a windbreak such as a hedge, fence or other structure to encourage butterflies to linger and help keep the taller plants from breaking over in strong wind.

Although butterflies obtain moisture from nectar, they still benefit from an available drink of water. A simple way to provide water is to sink a bucket or shallow pan of water into the garden soil. A birdbath can also function as a water source for butterflies, especially if a flat porous rock is placed in the water as a landing and resting site.

Finally, butterflies and caterpillars are easily killed or repelled by most garden insecticides. Protect butterflies and their caterpillars by using only low-toxicity insecticides such as insecticidal soap or horticultural oil only when necessary and spot-treat only those plants where insecticides are needed.

Butterfly Houses?

A popular addition to the garden is a birdhouse-sized structure intended to encourage butterflies by providing shelter. A butterfly house can be a charming and artistic addition to the garden, but the butterflies couldn't care less. Several studies have shown that the boxes are ignored by butterflies but are regularly occupied by spiders, wasps and mice. Still, butterfly houses can serve as a decorative announcement of your intentions to have a butterfly-friendly place. Happy butterfly gardening!

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