Issue of the Week: Monarchs and Milkweed


A massive fall migration has been occurring right under our noses in North America. It is not the typical talk of geese or caribou, which are known to travel thousands of miles between summer and wintering grounds. We’re talking about Monarch butterflies. In early fall, newly emerged monarch butterflies migrate up to 3000 miles to their wintering grounds in Mexico. Somehow they instinctively know where they are going, even though they themselves have never been there. If you have not noticed these fluttering canvases of art, you are not alone. Biologists are reporting a continent-wide decline.

Fewer monarchs are a part of a larger conservation issue, the decline of pollinators. Monarch butterflies, like bees and some other insects, are pollinators, and many of the world’s flowering plants and food crops depend on them to reproduce. Fewer pollinators can lead to a drop in food production and viable seeds needed to plant crops, dashing the hopes of home gardeners.

One of the main causes of monarch and other pollinator declines is loss of habitat. Loss of basic habitat requirements, in this case floral resources other than flowering crops that provide food to pollinators, is contributing to their decline. Unlike other pollinators, Monarch butterflies need a specific plant to complete their life cycle; the milkweed plant. Milkweed is the host-plant for the monarch butterfly larva, without it, the larva would not be able to develop into a butterfly.


Unfortunately, milkweeds are listed in some states and provinces as noxious weeds because they can be poisonous to cattle and other livestock. In some locations, it is difficult to improve habitat for monarch butterflies because of the noxious status of milkweed. In other places, milkweeds flourished in grasslands and road edges, but are now aggressively farmed and mowed. Large hedgerows between fields or buffer areas have been removed to maximize the real estate farmed. There are additional threats to monarch butterflies, such as the use of herbicides and pesticides, which have boomed during our agricultural revolution.

Eradication of milkweed is a threat to the monarch butterfly, but removal of hedgerows and open grasslands is impacting many other wildlife species as well. Partridge, quail and other grassland birds thrive in large, wide-open grasslands needed to nest and reproduce. These treeless areas are also important for birds of prey, such as American kestrels, northern harriers, and prairie falcons that rely on grasslands to hunt insects and small mammals. Pronghorn, elk, bison, and other grazing mammals all nourish themselves in grasslands.

Conservation programs are working to restore what has become the most uncommon habitat type, large grasslands, to ensure species like the monarch continue to prosper. Specifically, the Agricultural Act of 2014 – otherwise known as the Farm Bill – authorizes a range of incentive-based conservation programs on agricultural land. Many of these programs rely on conservation practices that can be used to create or improve pollinator habitat or incentives to keep fields out of crop rotations for extended periods of time. These programs also benefit a wide range of other species by helping to create suitable habitat.   Continually, if we work to create larger grasslands ungulates and other grazers will benefit. In this case if you build it and manage it, they will come.

Twice a week, SCI Foundation informs readers about conservation initiatives happening worldwide and updates them on SCI Foundation’s news, projects and events. Tuesdays are dedicated to an Issue of the Week and Thursday’s Weekly Updates will provide an inside look into research and our other science-based conservation efforts. Follow us on Facebook and Twitter for more SCI Foundation news. 

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