The Monarch Butterflies did not make it to Troy, Maine this year. Not the end of the world, as they say. Monarch migration pathes vary from year to year but still, it's disappointing and makes me take notice. We have lots of milkweed in Maine. Asclepias syrica and incarnata, common and swamp. It grows along the roads, in the fields and on the powerlines. What we do not have are Monarch butterflies. Why not?
As far as I can tell it's mostly a Roundup problem between here and wintering areas such as Florida or Mexico and everywhere in between, especially in the midwest. Roundup ready farmers spray everything that is not corn or soy including milkweed. Farmers are not the only ones that spray the deadly herbicide. The elimination of native plants better known as weeds is a mission in the suburbs and along the roadsides. If Maine's Monarches come from Florida up the East Coast, they are likely to find a food and breeding desert. The herbicide Roundup will eliminate weeds and at the same time disrupt the breeding cycle of pollinator insects.
One factor that makes the Monarchs so susceptible is that th cannot get from Mexico or Florida to Maine in one generation. Their lifespan is too short, so it takes several generations to make the trip and each generation needs milkweed to complete its breeding cycle. Every breeding cycle requires milkweed for pupation and native plants for food.
Up until now we have thought about protecting areas of special interest but now we need to start thinking in corridors. More than that we need to pay attention to the effects of our gardening and landscaping habits. Migrating animals of all sorts need to eat, pollinate, pupate. I am starting to devote more and more of my garden to pollinator/food plants, native plants that serve the birds, bees, and butterflies. In an era where we have projected a human handprint just about everywhere we need to step up and help.
Reductions in milkweed and agricultural regions of the United States
167 million acres of monarch habitat has been lost since 1996. The reduction in milkweed habitat in agricultural regions of North America has been cited as a major cause of population declines. Prior to the introduction of genetically altered corn and soybeans, milkweed was common in the crop fields. Conservationists cite the use of pesticides and herbicides as a cause of population decline. Public criticism of GMO crops continues of corn and soybeans which have Bacillus therigenes genes as part of their DNA, (pollen from these crops is thought to increase monarch mortality). that produce pollen that can fall onto larval host plants negatively impacts the survival of larvae. More acres of GMO crops are planted yearly, partly in demand for the ethanol that is required in gasoline, the so-called ethanol mandate, the Clean Energy Act of 2007The of a connection between the use of GMO crops and the decline in population has been called 'suggestive but not conclusive'. Milkweed habitat is also destroyed by the expansion of urban and suburban areas.