Monarch Butterflies Rule Wildwood in Fall
Usually, the cycle continues with the newly emerged adults laying eggs. But the monarchs of fall have a different fate. They can’t survive freezing temperatures in any stage: egg, caterpillar, chrysalis, or adult. So the adults that emerge in September and October defer reproduction and instead, migrate to Mexico. Gathering by the thousands in fir trees high in the mountains not far from Mexico City, they spend the winter using as little energy as possible.
Monarchs Need Milkweed
Monarchs will only lay their eggs on milkweed plants. Not many animals can tolerate eating these leaves because the thick, milky sap gums up their jaws. But monarchs manage just fine. The sap contains a cardiac glycoside, which is poisonous to birds and mammals. As the caterpillars eat, they use the nutrition to grow and they incorporate the toxin into their skin. The toxin stays there throughout the life cycle. The dramatic orange and black pattern serves as a warning that advertises “Caution: Stay away!” Birds or mammals that try to eat a monarch will gag, spit it out, and never try to eat anything similar again.
There are several species of milkweed; monarchs can use any of them as a host plant for the caterpillars. In our area Common Milkweed, Butterfly Milkweed, and Swamp Milkweed are popular. Planting milkweed will help the monarchs reproduce, while flowers with nectar provide the food the adult butterflies need to fuel their migration.
Tagging Monarch Butterflies
North American scientists didn”t find the winter roosting location of the monarchs until the 1970s. There are still questions to be answered about the migration. A citizen science project called Monarch Watch helps by gathering data on the butterflies and their migration.
Wildwood Park participates in Monarch Watch, tagging butterflies that are raised in the nature center or caught in the park. Before release, a sticker is attached to the wing. Each tag has an email address and a unique number. The date, tag number, sex, and location are recorded on a data sheet. All the information is sent to a database for scientists to use. Anyone who finds a tag reports the number, date, and location, helping scientists understand the migration.
How Wildwood Helps Monarchs
The park has milkweed growing in several areas to host monarch caterpillars, and nectar plants for adults. The nature center has a special exhibit every fall. Monarch caterpillars gathered in the park are raised in a Plexiglas container. Visitors can watch them eating milkweed and if they are lucky, may even see a chrysalis form or a butterfly emerge. Because these caterpillars are raised indoors, they are protected from predators that include insects and spiders.
Wildwood Park participates in Monarch Watch, tagging up to 50 monarchs each fall. In 2015, one of the monarchs raised in the nature center and tagged before it was released was recovered in El Rosario Preserve in Mexico.
At an annual festival called Celebrate Wildwood, the monarchs are on display for hundreds of visitors, who learn about these fascinating insects. They take home milkweed seeds to plant, encouraging monarchs in their own yard.
Things You Can Do To Help Monarchs
- Plant milkweed and nectar plants
- Go native – convert some of your lawn to gardens with native plants
- Decrease or eliminate the use of herbicides and pesticides
- Buy organic and non-GMO food
- Support preservation of land