How Butterfly Gardens Work

Butterfly Background
Ravenous caterpillars eat lots of host plants in preparation for their transformation into butterflies.
Ravenous caterpillars eat lots of host plants in preparation for their transformation into butterflies.
Photo by Jeff Foott, © Discovery Communications, LLC

Before you can create a butterfly garden alive with a profusion of delicately fluttering wings, you need to know a little about butterfly biology, including how they survive and reproduce.

When designing a butterfly garden, remember that butterflies are not always so attractive. They spend a crucial portion of their lives as caterpillars. The caterpillar, or larval, stage functions as the growth period. It may last as long as three years in colder climates or as briefly as 12 days in warmer ones. Caterpillars eat constantly, shedding their skin four or five times as they continually outgrow it, like kids in the thick of a growth spurt. Feeding mainly on leaves, caterpillars balloon to one thousand times their initial size by the end of the larval period [source: Dole].

Although caterpillars may eat with abandon, they often are highly picky. Some species only eat one type of plant. These preferred plants are called host plants, and you want to make sure you stock plenty of them in your garden. While it's true that different species will like different plants, typical host plants are weedy ones like clovers, nettles and dill.

Asters are a good nectar plant for butterfly gardens.
Garry Gay/Getty Images

Butterflies look out for their younger counterparts by only laying their eggs where emerging caterpillars are assured an abundant food source when they hatch. Females often fly from plant to plant, smelling with their antennae and tasting with their feet until they find the right spot. If females can't find the appropriate plant, they will not reproduce, so placing host plants in your butterfly garden is important.

Soon after a caterpillar transforms swan-like into a butterfly, it flies off in search of a mate. Just as the caterpillar phase is primarily for growth, the adult butterfly phase is primarily for reproduction. Butterflies do not grow. Rather than gobble down leaves for growth, butterflies mainly consume nectar for energy to fly. They find their food in flowering plants called nectar plants. Preferred nectar plants tend to be bright and colorful flowers where the nectar is easily accessible. Single petal flowers with short tubes and wide flat rims are a safe bet; phlox, verbena and flowers in the daisy or aster families are usually good choices. Successful butterfly gardens must incorporate a variety of both host and nectar plants.

In addition to catering to the energy needs of a butterfly's different life stages, butterfly gardens also need to account for the different hazards the insects may face, like a swarm of fierce fire ants. On the next page, you'll learn what types of threats caterpillars and butterflies might meet and how your garden can help to protect them.