Gardeners can help protect butterfly populations
Bees aren't the only pollinators suffering from a massive North American die-off. Butterflies and moths, those flying flowers of the insect world, are disappearing too.
"But the situation isn't hopeless," says Scott Hoffman Black, executive director of the Xerces Society for Invertebrate Conservation, in Portland, Oregon. "Anybody—gardeners or butterfly lovers—can make an oasis in their landscape for these important animals. It doesn't matter if you have a tiny lot or a farmyard. A little effort can help a lot."
Besides their beauty, butterflies and moths play a significant role in the pollination of flowering plants, 80 percent of which rely on animals—mostly insects—to move their pollen from plant to plant, the Xerces Society says. Butterflies and moths also serve as an important food source for other animals.
Yet in the United States alone, at least five butterfly species have gone extinct since 1950; an additional 25 are listed as endangered nationwide, and four are listed as threatened, according to Xerces in its new guide, "Gardening for Butterflies" (Timber Press, 2016).
Federal protection is being sought for the monarch butterfly population, which has plunged 90 percent in North America in less than 20 years. "During the same period, it is estimated that these once-common, iconic orange and black butterflies may have lost more than 165 million acres of habitat—an area about the size of Texas—including nearly a third of their summer breeding grounds," the Center for Biological Diversity says.
Just as significant has been the near elimination in farm fields of milkweed, the exclusive food of monarch caterpillars.
Donald Lewis, a professor and extension entomologist with Iowa State University, cites a 2012 study that documented an 81 percent decline in milkweeds in agricultural fields from 1999 to 2010.
"The cure for butterfly and pollinator preservation, conservation and improvement is to create biodiversity, which, of course, is at odds with most farming, urban sprawl and commercial development," Lewis said. "But it is our goal."
Nurture, enrich and diversify your home habitat, entomologists say.
Planting pollinator gardens that emphasize nectar plants that bloom year-round for bees, wasps and other wildlife is a good first step. Butterfly gardens take that a stage further by adding host plants suitable for hungry caterpillars.
"Since butterfly larvae are picky eaters, it takes a variety of food plants," Lewis said.
Butterfly gardens should be located where they'll get at least six hours of sun per day. They should contain at least four annual, biennial or perennial nectar plant species, and at least 10 milkweed plants of two or more types.
Ironically, beware the invasive butterfly bush, which has been listed as a noxious weed in several states. And think twice about the mass release of butterflies.
"Xerces is taking a stand that we should not be moving or releasing butterflies for such things as weddings, out of a concern for possible diseases," Black said. "We have a sense that the same issues that are happening with bees are happening with butterflies."
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