Bay Journal

To prevent monarchs from becoming rare, milkweed must stay common

  • By Kathy Reshetiloff on June 30, 2015
Clockwise from far left: A monarch, rests on a common milkweed.   (R. Harrison Wiegand / MD Department of Natural Resources) The monarch caterpillar is dependent on milkweeds for food.  (USFWS) A monarch butterfly rests on a butter-flyweed. (U.S. Fish & Wildlife Service)

The monarch butterfly is one of the most recognizable species of wildlife in all of North America. Easily identified by dark orange wings with black veins and white edge spots, this 4-inch butterfly is found throughout the United States, southern Canada and Mexico. They undertake one of the world’s most remarkable and fascinating migrations, traveling thousands of miles over many generations from Mexico, across the United States, to Canada.

North American monarch butterflies are in trouble. Threats, including loss of milkweed habitat needed to lay their eggs and for their caterpillars to eat, are having a devastating impact on their populations and the migration phenomenon.

Despite being ecologically important and an ornamental flower, many types of milkweeds have been eradicated from farms, suburban neighborhoods and cities. Even if the plant isn’t specifically targeted, commonly used, broad-based herbicides kill milkweeds. This, coupled with threats to the monarchs’ overwintering grounds in Mexico and California, has resulted in the precipitous decline of the insect’s population in North America

But any backyard can become an oasis for monarchs and other pollinators—even in cities. Schools, youth and community groups, businesses, and state and local governments can engage in planting native milkweed and protecting monarch habitat along roadsides, rights of way, and other public and private lands.

Habitat for monarchs can be anywhere, as long as there is milkweed growing there! Here are a few milkweed species native to the Northeast (and often easy to find at nurseries):

  •  common milkweed (Asclepias syriaca): sunny, dry areas
  •  swamp milkweed (Asclepias incarnata): sun to partial shade, moist to wet areas
  •  butterflyweed or butterfly milkweed (Asclepias tuberosa): sun to partial shade, dry to moist areas

Gardens, managed corridors, agricultural areas, and natural and restored areas can all provide monarch habitat. Key components for monarch habitat include at least one milkweed species that is native to your area that will provide food for monarch caterpillars; a mix of other native flowers with different bloom times to provide food for other butterflies and pollinators; and limited use or avoidance of pesticides, including herbicides and insecticides.

Vast tracts of land have been converted for residential areas, parks, schools and businesses. Butterfly gardens within these developed areas provide much-needed habitat for butterflies. These butterfly havens can be a few square feet within an urban backyard, or a larger managed garden attached to a corporate office park.

There are millions of miles of highways in the United States and millions of acres of land within utility rights-of-way. When managed appropriately, these areas can provide critical habitat for monarchs and other pollinators. A typical right-of-way managed for monarchs would include the initial removal of invasive and undesirable species, preparation of the surface through tilling and other means, planting of native flowering plants, and management through timed mowing and monitoring.

Agricultural fields used to be an important source of milkweed for monarch caterpillars. Milkweed was historically grown alongside crop plants, and provided abundant food for monarch caterpillars. But with the introduction of herbicide-tolerant crops, management has shifted from a till-based approach to the more widespread use of herbicides.

Farmers have an important role to play in the conservation of monarch butterflies. Farms across the continent are adopting pollinator-friendly practices like planting native milkweeds in unused portions of farms, using low-till or no-till practices and applying minimal, well-timed and least-toxic herbicides.

Natural areas, including nature preserves and parks, present excellent opportunities for milkweed plantings even in high traffic areas like trail margins, campsites and picnic areas. Coordinate mowing and other site management activities until butterflies have migrated from the area. Avoid using herbicides and, if needed, target applications for specific invasive species control.

The state of monarchs also reflects the health of the U.S. landscape and its pollinators. Monarch declines are symptomatic of environmental problems that also pose risks to food production, natural places that help define national identity, and our own health.

Conserving and connecting habitat for monarchs will benefit many other plants and animals, including critical insect and avian pollinators, and future generations of Americans.

To learn about monarchs, milkweed and pollinators visit:

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About Kathy Reshetiloff

Kathryn Reshetiloff is with the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office in Annapolis.

Read more articles by Kathy Reshetiloff

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