Iowa is the center of the monarch butterfly’s breeding range. However, the monarch butterfly population has declined over the last decade, according to surveys on the butterfly’s overwintering habitat in Mexico. There are many possible reasons for the decline, including extreme drought and flooding in the U.S. Midwest, logging in Mexico where the monarchs roost and a decline in the milkweed habitat according to ISU’s Department of Entomology and Department of Natural Resource Ecology and Management.
Monarchs depend on milkweed for laying their eggs and for caterpillar nutrition. Adult monarchs also rely on nectar-producing plants for nutrition to fuel their cross-country flight in the fall.
Milkweed is the cornerstone of a successful butterfly garden and planting a mix of both native and non-invasive annuals will entice more monarchs to your garden gates. These varieties are utilized as both host plant for caterpillars and a nectar source for butterflies.
Tip: all milkweed varieties should be planted in groups of at least six plants. (This can be a mix of the varieties of milkweed.) Otherwise, there is a good chance your monarch caterpillars will run out of milkweed!
Common Milkweed (Asclepias syriaca NGN) – is easily grown and can spread rapidly if seedpods are left to open. Flowers are a nectar source for many butterflies and leaves are a food source for monarch butterfly larvae (caterpillars).
Information: 3-4 ft high (flower height 6-8:); 8-12 in wide; sun; dry soil conditions; flower color purple; bloom time – June – September; Zone 3-9. They are drought tolerant, have fall color and fragrant flower. Deer resistant. Native Plant
The following information comes from Blank Park Zoo’s awesome program called Plant. Grow. Fly.
Why Are We Concerned – Pollinators are in decline due to a variety of reasons including global climate change, loss of habitat and feeding resources, and some modern agricultural practices. Butterflies, for instance, require large corridors of suitable habitat to navigate between nectar sources. Our increasing rates of development and expanding networks of roads have presented them with formidable challenges. According to Monarch Watch, butterflies lose habitat areas equivalent to the size of Illinois every 16 years – that’s an average of 2.2 million acres lost per year.
Butterflies require not only connecting high quality swaths of habitat, but also specific types of plants that help them to feed and reproduce: nectar plants and host plants, respectively. Each species of butterfly has specific sets of needs these plants must meet to be used. In Iowa, the majority of our butterflies need region-specific grassland plants. However, these plants are just as threatened as the butterflies they help: since European settlement, Iowa has lost more than 99.9% of its native tallgrass prairie. Iowa butterflies – and the habitats in which they live – need our help.
Host Plants: Pussytoes (Antennaria), Asters (Symphyotrichum), False Indigo (Baptisia), Lupine (Lupinus), Milkweed (Asclepias), Native Grasses, Violets (Viola), New Jersey Tea (Ceanothus americanus), Herbs-dill, fennel, curly parsley, Purple Prairie Clover (Dalea purpurea), Black-Eyed Susan (Rudbeckia), Sunflowers (Helianthus), and Penstemon (Penstemon)
Nectar Plants: Bee Balm (Monarda), Blazing Stars (Liatris), Coneflowers (Echinacea), Cosmos (Cosmos), Goldenrod (Solidago), Ironweed (Vernonia), Joe-Pye Weed (Eutrochium), Lantana (Lantana), Rugosa Rose (Rose rugose), and Zinnias (Zinnia)