Milkweed and Monarchs

Posted June 24, 2022 by Emma Hayes

The relationship between the majestic monarch butterfly and the humble milkweed plant is incredibly special. Monarch butterflies begin their lives on a milkweed plant–the only plant the adult butterfly will lay its eggs on. After the caterpillar hatches, they begin feasting on the plant’s leaves. As they eat, the caterpillars ingest toxins called cardenolides, the compound that gives adult monarchs their striking orange color and makes them toxic to any waiting predators. Those bright orange wings are a warning: “Back off! I won’t make a tasty meal.”

Planting milkweed is one of the easiest ways to support our local monarch butterflies. With this in mind, planting milkweed is a bit more than putting seeds in the ground. There is a bit more to consider before picking up the garden tools!

The Importance of Planting Native

Since monarchs can be found across the US, it makes sense that milkweed is found everywhere as well. There are many different kinds of milkweed around the US that have adapted to the specific climate and region they are found in.

With milkweed, its all about context–the milkweed in a single region is suited to help the monarchs in that area develop a certain way. There are some species of milkweed, like Common Milkweed (Asclepias syriaca), Swamp Milkweed (Asclepias incarnata) and Butterfly Weed (Asclepias tuberosa ) are all native species with large ranges, and are usually a safe choice to plant in a garden. However, Tropical Milkweed (Asclepias curassavica) is a different story. Tropical Milkweed is a common plant in many nurseries and garden stores. While it’s easy to grow, studies by leading monarch butterfly researchers suggest that A. curassavica can negatively affect monarch development and make monarch butterflies susceptible to disease. When buying milkweed (even if it is listed as healthy for monarchs) look or ask for the scientific name of the plant. If it’s Asclepias curassavica, keep looking elsewhere for a healthier alternative.

Luckily, experts in monarch butterfly research have made it easy to find the best species for any region in the US. Researchers at the Xerces Society have made milkweed guides to help people find the right milkweed for their gardens, and tools like the Western Monarch Milkweed Mapper and the Pollinator Resource Center make finding the right milkweed species quick and easy.

What does the Zoo do for Monarchs?

Make no mistake–the Cincinnati Zoo is wild for all things pollinators! The Zoo, our Bowyer Farm property, and the Rockdale Urban Learning Garden are all individually accredited by the National Wildlife Federation as certified Wild Habitat. There are a lot of efforts on Zoo grounds to research, support, and celebrate pollinators like the monarch.

The ZooTeen program offers a branch of citizen science known as BuzzTroop, where Teens ages 13-17 document the range of pollinators in the Zoo. The data collected by BuzzTroop is vital to pollinator research by universities in the state of Ohio.

Each year, the Zoo also celebrates the Monarch Festival. As a proud partner of the AZA SAFE Monarchs program and a supporter of JourneyNorth, the Zoo puts on a parade and festival dedicated to the migration of the monarch butterfly. This festival raises awareness specifically for monarch butterflies and provides a space to celebrate these amazing animals.

One of the best ways to get involved at the Zoo is by registering a garden with the Plant for Pollinators program. The Zoo launched the Plant for Pollinators challenge in 2019 to promote pollinator habitat in Cincinnati and beyond. Registering a garden (which can be as big as several acres or as small as a potted plant) raises awareness for pollinators and helps document the amount of space that is dedicated to pollinator habitat. Since 2019, the Zoo has registered over 2,500 pollinator gardens with Plant for Pollinators.

The Cincinnati Zoo is dedicated to securing the future of the monarch butterfly. With many ways to get involved, we at the Zoo invite everyone to join us in protecting and supporting this fantastic species!

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