Western Monarch Working Group Resource Library

The below resources have been compiled by individuals and organizations participating in Marin’s Monarch Working Group that is collaborating to conserve and protect the western monarch butterfly.

Organizations participating in this effort: California Department of Fish and Wildlife, Environmental Action Committee of West Marin, Environmental Forum of Marin, Goldridge RCD, Marin Audubon, Marin RCD, Monarch Joint Venture, One Tam, Point Blue, SPAWN, UC David Marin Master Gardeners, Xerces Society.

Coordination by Ed Nute, Marin Audubon Volunteer

Tropical Milkweed Trade Out Program

SPAWN continues to coordinate the Tropical Milkweed Trade Out Program where people can remove their tropical milkweed and receive free native milkweed in exchange. Tropical milkweed (Asclepias curassavica) is a plant that is familiar to most Bay-area gardeners. This non-native milkweed is a popular plant because many gardeners want to help support monarch butterflies. Unfortunately, tropical milkweed is problematic for western monarchs.

Problems caused by tropical milkweed:

• Tropical milkweed encourages adults to breed in the winter, which alters their migration patterns; adults lose energy and often don't survive winter.

• During the winter there is often not enough milkweed available to feed caterpillars through all stages of their development, leading to starvation.

• The majority of larvae and butterflies which develop during the winter don’t survive the cold temperatures.

• The few butterflies that reach the coast often carry large loads of OE and spread it to the overwintering grounds

Learn more about SPAWN’s program here and contact SPAWN Nursery Manager Audrey Fusco for more information. Audrey@tirn.org