Misconception #1: Milkweed is only useful to monarchs
Despite their natural toxicity, milkweeds are utilized by a variety of insect species.Butterflies, moths, bees, and wasps and more visit milkweeds for pollen and/or nectar. Regional studies examining milkweed pollination found over two dozen insect species using milkweeds; and results indicate that honey bees, bumble bees, other large bees, large wasps, and larger butterflies were the most important milkweed pollinators.
Misconception #2: You should not grow milkweed plants because they are dangerous to livestock, pets, or children
Although milkweed contains toxins, it rarely poses any significant threat to people or animals. The name milkweed derives from the milky sap contained in the stems and leaves of the plant. The sap contains toxins called cardiac glycosides or cardenolides, which are known to be toxic to animals if consumed in large quantities. The amount of toxin in the plant varies by milkweed species. A small taste of milkweed is typically not fatal to animals, but can be dangerous if large quantities are consumed. Medicinal uses of milkweed have been documented, but outside of such traditional practices any part of the milkweed plant should not be consumed by humans. Milkweed has a foul taste, and it is not likely that children would consume the plant. Take steps to prevent accidental ingestion, such as instructing children that the plant is poisonous and to avoid any contact with their eyes after touching the plant. Remember to always wash your hands thoroughly after handling milkweed. Milkweeds are generally not sought after by grazing livestock or other animals when sufficient forage is available. According to the USDA, poisoning typically occurs when animals are concentrated in areas of poor forage and abundant milkweed stands. Prepared feeds and hay should not contain high concentrations of milkweed. Pets may encounter milkweed growing in naturalized areas or in pollinator gardens, but consumption is rarely reported. While rare, if human or animal milkweed poisoning is suspected, seek medical attention.
Misconception #3: Milkweed is an invasive weed
There are many species of milkweed native to North America and while “weed” is part of their name, these milkweeds are native, beneficial wildflowers. In the U.S., neither the federal government nor any states list milkweeds as noxious weeds. In fact at least five species are listed as state or federal endangered species. According to the North American Invasive Species Network, an invasive species is “a non-native species, whose introduction causes or is likely to cause economic harm, environmental harm, or harm to human health.” The invasiveness of any plant depends on the characteristics of the species and where it is planted. Some species of milkweed, like common milkweed (Asclepias syriaca), have a tendency to be more aggressive in garden settings or disturbed areas, and thus have a reputation of being “weedy”.
Misconception #4: Monarch caterpillars will eat more than milkweed
Milkweed (genus Asclepias) is the only host plant for monarch caterpillars, Female monarch butterflies know that their offspring can only eat milkweed, and thus are drawn to milkweed species to lay their eggs. There have been some reports of egg-laying in the wild on plants like non-native, invasive swallow-worts, but monarch caterpillars cannot survive on these plants and ultimately starve to death. In addition, other species of butterfly whose caterpillars look similar to monarchs but feed on plants other than milkweed can cause confusion upon casual observation. For example the Black Swallowtails.
For more information about milkweed misconceptions, please visit, Monarch Joint Venture.