The monarch butterfly (Danaus plexippus) population east of the Rocky Mountains has declined for many reasons, but loss of milkweed (Asclepias spp.), its’ larval host plant, in the U.S. Midwest, is a contributing factor. To help increase the monarch population, an estimated 1.6 billion stems of milkweed weed to be established in this part of the country. To help meet this goal, Iowa’s conservation plan calls for establishing 0.13 to 0.19 billion stems over the next 20 years, which equates to approximately 480,000 to 830,000 acres of monarch habitat.
One strategy for increasing monarch habitat is to plant prairie seed mixes that include milkweed for larval development and a variety of flowering species with bloom periods that span from April to October to provide forage for monarch adults and other pollinator species (e.g., see https://store.extension.iastate.edu/product/Monarch-Seed-Mix-High-Diversity). Observations of monarchs interacting with floral species could help identify preferred forage plants for monarch adults.
In 2017 and 2018, monarch butterflies were caught on prairie plants and used for other research experiments. Monarchs were collected on many plants, but they were most frequently collected on common milkweed, wild bergamot, red clover, butterfly milkweed, prairie blazing star, and musk thistle (Table 1). If these plants can already be found in your field or yard, you are contributing to restoring the monarch population! Not all of these species are native to Iowa, but if you are interested in planting habitat for monarchs and pollinators, consider including these species in your seed mix.
Table 1: List of monarch captures on blooming plant species.
Check if plants are native or introduced
Selected References:
Brower, L. P., O. R. Taylor, E. H. Williams, D. A. Slayback, R. R. Zubieta, and M. I. Ramirez. 2012. Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk? Insect Conserv. Diver. 5: 95–100. doi:10.1111/j.1752-4598.2011.00142.x.
Oberhauser, K. S., R. Wiederholt, J. E. Diffendorfer, D. Semmens, L. Ries, W. E. Thogmartin, L. Lopez-Hoffman, and B. Semmens. 2017. A trans-national monarch butterfly population model and implications for regional conservation priorities. Ecol. Entomol. 42: 51–60. doi:10.1111/een.12351.
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