One of the most widely recognized butterflies in North America, the monarch, is disappearing fast. Most of that decline is blamed on changing land use, but property owners can help shore up the population by setting aside monarch "way stations" filled with milkweed and other nectar-rich plants.
The extent of the milkweed-monarch habitat loss since 1996 is believed to be an area roughly the size of Texas, said Orley (Chip) Taylor, an ecology professor at the University of Kansas and founding director of Monarch Watch, an education, conservation and research group.
"We're not looking at extinction, but the migration could decline to the point at which recovery could take many years -- if ever," Taylor said.
In the 1990s, up to one billion monarchs made the flight each fall from the northern U.S. and Canada to the oyamel fir forests north of Mexico City, and more than one million overwintered in forested groves on the California coast, according to the Xerces Society. "Now, researchers and citizen scientists estimate that only about 56.5 million monarchs remain, representing a decline of more than 80 per cent from the 21-year average across North America," the conservation group said.
Any monarch recovery effort will take a broad commitment beyond just the agricultural sector, Taylor said.
"The monarch migration will not be saved unless there is both a bottom-up (citizen-driven) and top-down (government) commitment to the restoration of habitats," he said.
The most effective response is planting monarch "way stations" or habitats in non-crop areas -- on school grounds, along roadsides and rights of way, in parks, businesses, residential areas or other unused sites, Taylor said. These plots can provide the resources needed to produce successive generations of monarchs and sustain them during their migration.
Way stations can be placed in or near existing gardens and should be at least nine square metres in size. Butterflies and butterfly plants need at least six hours of sun per day. It's best to have at least 10 plants made up of two or more milkweed species so they will bloom at different times during the growing season.
"We have over 10,000 registered way stations," Taylor said. "The truth is, we need 10 million or more."
Seventy-three different species of milkweed are known to exist in the U.S., Taylor said. These are the only plants on which the monarchs deposit their eggs and on which their larvae feed. No milkweed, no monarchs.
Milkweed seed is easy to collect in the wild but the percentage of seed that germinates varies, said Erwin (Duke) Elsner, an entomologist with Michigan State University Extension.
"Some insects feed on the seeds," Elsner said. "They look good but may not be viable. Harvest more than you think you'll need for success."
Milkweeds are aggressive propagators, spreading via underground rhizomes, so be careful where you plant them. The seeds also must be exposed to chilly, moist conditions before they will sprout.
Milkweed is available from many nurseries around North America specializing in wildflower seeds and plants.
"We used to get comments about milkweed being a noxious weed but we don't hear that from people anymore," said Bill Carter, president of Prairie Moon Nursery in Winona, Minnesota. Minnesota's transportation department "even began putting some milkweed in its roadside (seed) mix a couple of years ago."
