Asclepias speciosa is a specific
monarch butterfly food and
habitat plant. Additionally, phenylacetaldehyde produced by the plants attracts
Synanthedon myopaeformis, the red-belted clearwing moth. It is also a larval host for the
dogbane tiger moth and the
queen butterfly.
Monarch Watch provides information on rearing monarchs and their host plants. Efforts to restore falling monarch butterfly populations by establishing
butterfly gardens and monarch migratory "waystations" require particular attention to the target species' food preferences and population cycles, as well to the conditions needed to propagate and maintain their food plants. For example, where it grows in Michigan and surrounding areas and in the
western US, monarchs reproduce on
A. speciosa, especially when its foliage is soft and fresh. Because monarch reproduction in those areas peaks in late summer when milkweed foliage is old and tough,
A. speciosa needs to be mowed or cut back in June or July to assure that it will be regrowing rapidly when monarch reproduction reaches its peak. The seeds of some milkweeds need periods of cold treatment (
cold stratification) before they will germinate. To protect seeds from washing away during heavy rains and from seed–eating birds, one can cover the seeds with a light fabric or with an layer of
straw mulch. However,
mulch acts as an
insulator. Thicker layers of mulch can prevent seeds from germinating if they prevent soil temperatures from rising enough when winter ends. Further, few
seedlings can push through a thick layer of mulch. == Uses ==