Monarch butterflies need help! I’m frustrated to see tropical milkweed (Asclepias curassavica) for sale at my local nursery. This is my open letter to ask people to stop planting it in the U.S. & to ask responsible nurseries to stop selling this plant! 1/

Why? Because many uninformed (or partially informed) customers will plant this popular milkweed thinking they’re helping monarchs , but tropical milkweed is actually hurting monarchs. It is non-native milkweed & is causing a couple big problems. 2/

First, tropical milkweed causes a parasite problem when it is planted in temperate areas where it doesn’t die back in winter. Ophryocystis elektroscirrha (OE) is a parasite to monarchs & is deposited on leaves when monarchs feed. 3/

When caterpillars hatch & eat the plant, they ingest the OE parasite. When native milkweeds die back after blooming, the parasite dies with it, so each summer’s new monarch population feeds on OE parasite-free foliage. 4/

But in temperate regions, tropical milkweed is evergreen through the winter months and this allows OE parasite levels to rise on the plant, so future caterpillar generations feeding on the plant are exposed to high levels of OE. 5/

High levels of OE in monarchs are linked to lower migration success in the eastern population, reduction in lifespan & mating success, as well as body mass & flight ability. Secondly, tropical milkweed interferes with monarch migration & reproduction. 6/

When it is grown in northern areas, it can grow later in the year than native species & this confuses monarchs into breeding at a time when they should be migrating. 7/

In CA, where tropical milkweed is commonly grown, if grown near overwintering sites along the coast, it can spur monarchs to breed when they should be overwintering. 8/

In summary, if you live in U.S. please do not grow this plant and if you work at a nursery, please do no sell this plant! I am so fired up about milkweed today but the frustration is because of my love for butterflies!

I love butterflies so much I even have a monarch butterfly dress!

I want to clarify monarchs cannot survive without milkweed, the issue is that people need to plant NATIVE MILKWEED SPECIES. There are 100+ species of milkweed in the U.S. Here is a guide to native species by region: https://monarchjointventure.org/images/uploads/documents/MilkweedFactSheetFINAL.pdf