Monarch decline cause for concern

Joyce Wagner
In Motion Staff Writer

Monarch butterfly populations are suffering because of pesticides and herbicides that destroy their food supply, milkweed.
Photos by: Joyce Wagner/ In Motion[/caption]Southern Mexico is known as the winter destination for Monarch Butterflies. Unfortunately, the number of monarchs arriving there each year for their annual migration is declining. Reporting a 44 percent drop, 2013 marked the lowest return ever with 1.65 acres occupied by the monarchs compared with 2.93 acres the year before. Butterflies are measured by the acreage they occupy instead of trying to count individuals since they live in clumps of thousands. How can we slow or even reverse this downward trend? There is no quick, simple answer. Several factors contribute to this decline, including loss of habitat, climate changes and pesticide use.

Milkweed, the plant monarch caterpillars eat almost exclusively, used to grow in abundance throughout the country. Open fields of wild flowers have been mowed down, making room for “progress” in the form of houses, shopping centers and roadways. Illegal logging in Mexico has destroyed valuable roosting sites for these beautiful, colorful insects. While Mexico is working on measures to protect their habitat by developing and protecting sustainable areas for the butterflies to migrate to, Canada has actually removed some of the protection for the monarch butterfly habitats.

Monarchs migrate to Mexico and southern California for the warm winter climate. A body temperature of less than 86 degrees will prevent the monarch from flying. During this time they will bask in the sun or “shiver” their wings to warm themselves. While dry, they are able to survive below freezing temperatures. Once wet, dropping temperatures will quickly kill them. In 1991, an unusually cold, wet winter in Mexico killed about 70 percent of the monarch butterflies that had migrated there. The rain and freezing temperatures caused them to freeze to death. The loss resulted in lower numbers returning north than usual. Some areas haven’t seen them since.

Glyphosate, the main ingredient in many herbicides, including Roundup, has been linked to the reduced numbers of milkweed plants growing in this country. As a weedkiller, glyphosate has helped farmers and businesses control unwanted weeds efficiently. One of the reasons such a strong herbicide is necessary has been the use of Genetically Modified Organisms, or GMO’s as they are commonly called. GMO’s have created herbicide-tolerant crops such as corn and soy. Farmers and other land owners can quickly get rid of weeds without harming their food crops. Unfortunately, a lot of beneficial plants are lost this way. Most notable for the monarchs is the milkweed. While the butterflies live off of nectar from any plants, the larva, caterpillars need the milkweed to live and grow. It is on these plants that the butterfly lays her eggs. In 1996, monarchs occupied 44.5 acres of forest in Mexico. This was the greatest number recorded. It was also the same year that GMO’s were commercially planted for the first time. The monarch butterflies have been on the decline ever since.

Caterpillars that eat the milkweed plant, store the toxin in their system, making them taste bad to predators, who quickly learn not to eat them. A naturally hardy insect, the monarch is facing enemies they cannot protect themselves against. Limiting the use of herbicides and insecticides around homes and business will help. Check the ingredient list to see if it contains glyphosate. Many non-toxic alternatives are available with far less damage to the ecosystem. Planting milkweed is a low cost way to help these and other butterfly varieties survive. Small measures by many people add up to make a huge difference. If you plant it, they will come. Then it’s a matter of sitting back, relaxing and watch the butterflies flutter by.