Last week, a crowd of around 25 people gathered at the Colusa National Wildlife Refuge to hear more about monarch butterflies and milkweed, and how they can help to save California’s struggling population.
Put simply, monarchs cannot survive without milkweed. Monarchs lay their eggs exclusively on the plant, and the caterpillars that hatch from the eggs eat only milkweed. With changing land management practices, including the development of rural lands, and the use of mowing and herbicides to control roadside vegetation, the abundance of milkweeds in California has been drastically reduced.
The Sacramento National Wildlife Refuge Complex, the UCCE Master Gardeners of Colusa County, and The Xerces Society for Invertebrate Conservation, are working collaboratively to create new sources of milkweed seed and to inspire locals to plant milkweed in their gardens and to help off-set some of those losses, which they discussed at length on Saturday.
According to The Xerces Society, the migration of monarch butterflies from the Eastern U.S. to the mountains of central Mexico is a widely known phenomenon, but fewer people are aware of a smaller migration of monarchs from the breeding areas in the West to the California Coast, and in some cases, to the mountains of central Mexico. The butterflies begin breeding and departing from overwintering sites – hundreds of small, wooded groves along the California coast, some of which host thousands of wintering monarchs – in late winter and early spring, moving throughout the inland West as they search for milkweeds on which to lay their eggs.
“How they know – if you imagine flying over the Colusa Basin here, as a tiny little insect, and you can find that one little plant, I don’t know how they do it. It’s amazing,” said Lora Haller, of the United States Fish and Wildlife Service. “There’s a lot of things we don’t understand yet.”
Once hatched, the caterpillars feed on the milkweeds for up to two weeks before forming chrysalises, and emerge as adult butterflies eight to 10 days later. Over the course of the spring, summer, and fall, these butterflies continue to breed successive generations throughout the inland West where milkweed occurs, heading north toward Washington and Idaho and east toward the Rocky Mountains. Those generations of monarchs born in late summer or early fall will then migrate back to the California coast, and start the process anew.
According to the Xerces Society’s annual census of monarch butterflies overwintering along California’s coast, populations in western North America are at their lowest point in five years, despite recovery efforts – which is part of the reason for the cooperation between the USFWS, the Xerces Society, and the UCCE Master Gardeners of Colusa County that was on display this weekend.
“What can you do? You can plant milkweed,” said Haller. “That’s one of the best things to do.”
There are two primary kinds of milkweeds native to the Colusa County area: Showy milkweed (Asclepias speciosa) and Narrow Leaf Milkweed (Asclepias fascicularis), Haller said. At various locations on the Sacramento National Wildlife Refuge Complex, including the Colusa National Wildlife Refuge, the USFWS has both species planted in native gardens, which are being used for seed-stock. With help from volunteers, USFWS staff have gathered seeds from the plants in their native gardens for the past five years, and have distributed them to various area residents. Among those who received seeds were a handful of Colusa County Master Gardeners, who germinated the seeds and produced ready-to-plant milkweed sprouts.
The plants aren’t exactly conducive to “organized landscaping,” as Master Gardener John Vafis pointed out: While they have a hard time competing with other plants, they also have a propensity for spreading into areas they aren’t wanted.
“We need to create places where these can grow, and I’m thinking of areas in our community where we might be able to set up these plantings, where we could put this stuff and let it grow –along the river or wherever,” said Vafis.
In addition to planting native milkweeds, Haller added that having native flowers out to help provide nectar for the adult butterflies, supporting organic and GMO-free agriculture, and avoiding the use of insecticides and herbicides – or at least avoiding using them on the plants you want to keep your monarchs on – are all ways to assist the struggling population of butterflies. ■