Planting butterfly weed vs other milkweeds- lack of toxins?
Should I be propagating other varieties of milkweed in my gardens as opposed to butterfly weed? It is my understanding that butterfly weed does not have the milky sap/toxins Monarchs need to protect themselves from predators. I currently have common milkweed and butterfly weed in my gardens. Over the past three years, I have not observed any Monarchs laying eggs on the common milkweed vs. the butterfly weed. I'm curious why the Monarch's are consistently choosing the butterfly weed over the common milkweed?
First of all, I’d like clarify that we are talking about butterfly milkweed (Asclepias tuberosa) and common milkweed (Asclepias syriaca). Some recent research suggests that adult female Monarch butterflies are more likely to lay their eggs on some types of milkweeds more than others. This is an active area of research and scientists are working to determine the factors involved. The study can be found here: https://doi.org/10.1007/s10841-018-0069-5 The bottom line is that both milkweeds are suitable food plants for monarch caterpillars and they provide nectar for the monarch butterflies and a variety of other pollinators. Growing more than one milkweed species provides diversity for you and for the beneficial insects so I’d say it’s a win-win! Here is a MSU Extension website with some more info as well: https://www.canr.msu.edu/resources/smart_gardening_to_support_monarchs