If you have seen a Monarch butterfly the past few years, you were indeed fortunate. Populations west of the Rocky Mountains have declined greatly since 1991. Scientists list contributing decline factors as: loss of habitat, destruction of larval food (milkweed is the only plant Monarch caterpillars will eat) roadside cutting, spraying of herbicides and pesticides, infestation by a protozoan parasite and extreme weather at wintering sites. Overwintering sites in the Mexican states of Chihuahua, Veracruz and Baja California report that up to 30 percent of the 50-60 million butterflies that migrate to the United States may have been killed by frigid temperatures this past winter when temperatures plunged to 11 degrees Farenheit. However, two sanctuary sites at Pacific Grove on the Monterey Peninsula (California) reported having 50,000 butterflies successfully overwinter at their retreat.
The Pacific Grove Sanctuary is a volunteer conservation program through "Friends of the Monarchs". This group provides a docent program for the public as well as assisting with Monarch butterfly research. Butterflies are usually in full number by Thanksgiving and tend to have moved on by the end of February. A second, nationally based program "The Monarch Program" is a research based group with staff botanists and lepodopterists and a 10-12 page monthly research newsletter. The group promotes seed and plant sources and tours to Mexico to view the wintering butterflies.
How can Oregon Master Gardeners help? Report any sighting of a Monarch by calling 1-800-60-MONARCH. Plant butterfly nectar sources and larval food (milkweed). Protect known milkweed patches. Join a Monarch advocate group.
Milkweed species are generally annuals in Oregon. The Showy Milkweed, Asclepias speciosa is an Oregon native, grows 2-4 feet tall with large pink midsummer flowers. Common Milkweed, A.sclepias syriaca is found in Eastern Oregon. It blooms early-mid summer. Clump forming and 3-4 feet tall, this species has somewhat downy or felty leaves and dense lightly fragrant inflorescences variable in color from faint pink to deep rose. Goodwin Creek Gardens, PO BOX 83, Williams, OR 97544 (1-503-846-7357) has a selection of milkweed seeds and plants including Orange (tuberosa), Showy (speciosa), Swamp (incarnata) and a tropical that does well in Oregon.
Lola Short, a Roseburg area butterfly advocate, has provided Douglas County Master Gardeners with milkweed seeds and information on the butterflies. Lola is happy to take questions or calls regarding the Monarch butterfly at 1-541-672-3429.
Other references: American Butterflies May 1993, Oregonian Jan 1996, "The Monarch Program", PO BOX 178671, San Diego, CA 92177, phone 1-619-944-7113.