Roadside Habitat for Monarchs: Monarch Butterflies, Weeds, and Herbicides

Author: Xerces Society Date: 2019

Monarch butterflies are in decline in North America, and restoring monarch habitat, including roadsides, is important to the species’ recovery. Monarch caterpillars require milkweed (primarily in the genus Asclepias) to complete their development. A diversity of milkweed species is found on roadsides, and monarchs lay their eggs readily on milkweed plants in roadsides and consume nectar from milkweed flowers.

Roadsides provide more than just milkweed. They can also provide diverse nectar sources to feed adult monarchs and other pollinators—but ensuring that roadsides can continue to provide the best habitat requires some thought and care. This guide highlights best management practices to reduce the impacts of herbicides on monarchs.

Download PDF: Roadside Habitat for Monarchs: Monarch Butterflies, Weeds, and Herbicides (548KB)

Managing Milkweed Crop Pests: A Native Seed Industry Guide

Author: Project Milkweed Date: 2017

Project Milkweed is a collaboration with the Xerces Society, the native seed industry, and the USDA Natural Resources Conservation Service (NRCS) to increase commercial availability of milkweed seed. Since 2010 this partnership has worked to address some of the major production challenges faced by the native seed industry and has expanded commercially viable milkweed production to regions where seed was not previously available.

During Project Milkweed surveys of native seed producers, yield loss from insect pests was consistently the most significant challenge reported. Further complicating the situation is the abundance of monarch butterfly caterpillars, crop pollinators, and predatory insects, all of which are typically found in seed production plots and which are vulnerable to insecticides used for pest control.

Download PDF: Managing Milkweed Crop Pests: A Native Seed Industry Guide (3MB)

Why Grow And Sell Native Milkweed?

Author: Monarch Joint Venture Date: unknown

Milkweed plants (family Asclepiadaceae) are the only food source for monarch butter y caterpillars. However, milkweed has severely declined in North America due to drastic changes in land use or management, like agriculture and development. Milkweed losses and other stressors are associated with declines in migratory monarch butterflies over the past 20 years [1, 6, 7]. To compensate for the loss of milkweed, gardeners across North America are helping monarchs by planting native species of milkweeds, and by keeping milkweeds safe from pesticides.

Download PDF: Why Grow and Sell Native Milkweed? (839KB)

A Guide to the Native Milkweeds of Oregon

Author: The Xerces Society Date: 2012

Five species of milkweed are native to Oregon. This guide includes profiles of the four most common species, all of which are used as a larval host plant by the monarch butterfly.

Asclepias cordifolia (purple milkweed, heartleaf milkweed)
Asclepias cryptoceras ssp. davisii (Davis’ milkweed)
Asclepias fascicularis (narrow-leaved milkweed)
Asclepias speciosa (showy milkweed)

A profile of each of these species includes descriptions of flowers, leaves, and seed pods, accompanied by photos and distribution maps. Supporting these profiles is a simple guide to identifying milkweeds based on their distinctive flowers and fruits.