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Butterfly Populations Decline: How Gardeners Can Help

A recent investigation into the dwindling populations of butterflies, published in the journal Science, brought significant attention when it was released in March. The New York Times responded by creating an interactive tool enabling readers to see the impact on butterfly populations in their local areas. The study’s authors emphasized the need for urgent conservation measures to protect butterflies, stating, “the prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.” With this dire news at hand, many may wonder how they can contribute to the conservation of these essential pollinators.

Mary Anne Borge, editor of Butterfly Gardener, a publication of the North American Butterfly Association, offers practical advice: focus on planting food for caterpillars. Traditionally, discussions around butterfly gardening revolve around providing nectar sources for adult butterflies. Borge notes, however, that caterpillars—who are the juvenile stage of butterflies—also require specific plants for nourishment. “If you genuinely want to support butterfly populations, you need to provide food for the caterpillars as well as nectar for the adults,” she explains.

Caterpillars are notoriously selective about their diets. These larvae typically only consume specific host plants that correspond to the butterfly species. A prominent example is the famous milkweed utilized by monarchs; however, there are many other crucial caterpillar-host plant relationships. For instance, the zebra swallowtail caterpillar feeds exclusively on the pawpaw tree (Asimina triloba). While some caterpillars like the monarch and zebra swallowtail are restricted to one type of plant, others may thrive on several different plants. Nevertheless, most caterpillars cannot eat ornamental plants that are non-native.

The choice of plants to support caterpillars will vary depending on geographical location. The National Wildlife Federation’s plant finder tool can assist gardeners by allowing them to enter their zip codes to identify local butterflies and corresponding host plants suitable for their gardens. Borge also highlights the importance of considering nearby plant species outside one’s immediate region. She remarked, “I found it very fascinating to look at the regional data from that report in Science. It indicates interesting trends: butterflies that once flourished in the southern United States are now rising in numbers in northern regions. The key to this is having the caterpillar food plants available that they require.”

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www.gardenista.com