What's the Issue?

There are specialized relationships that have evolved over time between plants and insects. These relationships are referred to as symbiotic, and they are vital to the life cycle of many pollinators. One of the most notorious symbiotic relationships is between the monarch butterfly and milkweed plant species. Adult female monarch butterflies lay their eggs on milkweed and their larvae feed and depend on the plant for survival. 

Invasive plants such as pale and black swallow-worts can easily overtake areas where milkweed and other beneficial native plants grow. When this happens, the life cycles of monarchs and other pollinators are impacted. 

What You Can Do To Help

  • Introduce milkweed and other pollinator host pants to your property (see videos below).

  • Learn more about monarch butterfly migration.

  • Learn about native plants for pollinators and beneficial insects in the Great Lakes region in this great guide created by the Xerces Society. 

  • Search for and remove swallow-wort and other invasive plants from your property (see swallow-wort management details below).

Growing Milkweed

Harvesting and Planting Milkweed Seeds

Identifying Swallow-wort

Native to Ukraine, parts of Russia and the Mediterranean regions of Europe, black and pale swallow-wort were introduced as ornamental plants in the 1800s. They are perennial, herbaceous vines that grown dense stands that smother out understory vegetation and trees. Swallow-worts also release toxins into the soil that make it unsuitable for other plants to grow.

Learn More About Swallow-wort

Management Options

Prevention: Once established, swallow-wort is difficult to control. Monitor for populations in late summer, when the plants turn golden yellow and pods are present but not open. Stay out of infested areas during seed dispersal to prevent seed dissemination to unaffected areas. Likewise, clean your boots, ATVs, and other equipment when coming out of infested areas.
 
Initial control efforts should concentrate on plants in sunny areas since they will produce the most seeds.
 
Physical/Mechanical Control: Small patches can be dug out by hand. The entire plant must be removed and destroyed. To prevent seed dispersal, pods should be removed before they open and then burned. Large stands can be managed by consistent mowing when pods are very small (May-July). Controlled burning is not effective and may improve site conditions for swallow-wort seedling establishment.
 
Chemical Control: Triclopyr or glyphosate can be applied to foliage prior to seed set typically in late June to mid-July for the northern New York region. The use of surfactants helps herbicides penetrate the waxy leaf coating. Be sure to follow all instructions on chemical labels.

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