Situation Grim But Not Hopeless for Monarch Butterflies
Scientists have just released this year’s report on the number of Monarch butterflies overwintering in Mexico. Those numbers, measured in the amount of land occupied by Monarch colonies, vary from year to year. The last three years, however, have all been at historic lows.
There was an increase over last winter, from 0.67 to 1.13 hectares – compared to an average of 9.2 hectares from 1994 to 2004. (A hectare is about 2.5 acres.)
From this we can take heart that Monarchs are not yet doomed, but we should not kid ourselves. Scientists tell us that a Monarch population this small is extremely fragile and vulnerable to extinction.
It’s frightening to think that the Monarch migration could be wiped out through the destruction of less than three acres of Mexican forest. Hard to believe as these were such a common butterfly when I was a kid.
Leading scientists and conservationists have petitioned the US Fish and Wildlife Service to declare the Monarchs a threatened species under the Endangered Species Act, triggering a process that will last a year. If they are found to be threatened, the door would be opened to government action (and also, no doubt, prolonged and bitter political battles).
In the meantime, North American gardeners can and should plant milkweed (Asclepias), the only genus of plants that are hosts to Monarch caterpillars. The biggest single cause of the Monarch decline has been the use of herbicides on fields of genetically modified crops. This has caused Milkweeds, once common, to virtually disappear from Midwestern farm fields.
In my home state of Illinois, there are 1.4 million acres of lawn. There is no good reason why Butterflyweed (Asclepias tuberosa) shouldn’t be as common here as Marigolds on home, public, and commercial landscapes. If that were to happen, it could substantially increase the number of way stations for the Monarch migration. Of course, there are many other garden-worthy Milkweeds that could also be used.
This is not to say that agribusiness should be let off the hook. All that Illinois lawn is dwarfed by our 22 million acres of cropland, mostly corn and soybeans. Even so, the crisis is now, and we should do what we can in the present.
The new Monarch numbers have prodded me to increase the number of Milkweeds I was planning to put in this Spring. I already have quite a few Swamp Milkweeds (Asclepias incarnata) and Butterflyweeds, as well as a couple of Purple Milkweeds (Asclepias purpureum). In April or May I’ll be putting in more Butterflyweed, and I may even try some Whorled Milkweed (Asclepias verticillata), which is supposed to be short and well behaved.
Do you already have Milkweeds in your garden? If not, will you plant some this spring?