LANSING, Mich. (AP) — Michigan has recently enacted a law designed to combat the spread of noxious weeds while also offering protection for milkweed, a crucial plant for monarch butterflies. The legislation aims to eradicate specific noxious weeds and grants local government bodies the authority to appoint commissioners and allocate funding for the control of these plants.
Under the new law, certain plants including Canada thistle, dodders, wild carrot, poison ivy, and poison sumac are classified as noxious weeds. Additionally, any plants deemed a “common nuisance” can also be included in this category. However, the law explicitly excludes milkweed from the definition of noxious weeds.
Milkweed, known for its importance as a food source for insects, particularly monarch caterpillars, is widespread throughout Michigan. It can be found in various habitats such as fence rows, roadsides, fields, prairies, and pastures. Although it can tolerate light shade, milkweed thrives in full sun.
The United States Department of Agriculture (USDA) identifies common milkweed as a vital food plant for insects, attracting over 450 species. Monarch butterflies solely rely on the leaves of milkweed plants during their caterpillar stage. However, the decline in milkweed populations has led to a decrease in monarch butterfly populations. To support monarchs, planting milkweed offers a vital food source.
While milkweed contains cardiac glycoside compounds that make it toxic to most insects and animals, some insects have developed a defense mechanism by storing these compounds in their tissue. This renders them inedible or toxic to other animals. Monarch butterflies utilize this defense, deterring birds from consuming them or their caterpillars. Although northern monarchs feeding on common milkweed have relatively low toxin levels and are likely safe to eat for birds, this perception is not known to the birds. Monarchs further south are probably toxic to birds.
Michigan State University Extension reveals that approximately a dozen native milkweed species can be found in Michigan. This diversity of milkweed plays a crucial role in supporting monarch butterfly populations in the state.
The new law aims to strike a balance between addressing the threat of noxious weeds and preserving the essential role of milkweed for monarch butterflies. By offering protection to milkweed and prioritizing its preservation, Michigan hopes to create a more favorable environment for monarchs to thrive.