Monarch caterpillar on milkweed, â€śEating timeâ€ť by U.S. Fish and Wildlife Service - Midwest Region is licensed under CC BY 2.0.
With their stained-glass wings of orange and stark black, Monarchs seem to top the list of most loved butterflies, at least for people living along their migratory path from Canada to Mexico. These beauties are hearty enough to fly up to 3000 miles, riding the currents and thermals from as far north as Canada to reach the warmth of Southern California and Mexico for the winter. But they cannot exist without the caterpillarâ€™s only food source, milkweed.
According to the Center for Biological Diversity (CBD), the monarch population has decreased by 53 percent over the past year. This statistic was described as â€śheartbreakingâ€ť by a senior scientist at the CBD. One reason for the crisis is the use of herbicides which kill milkweed. Poor weather conditions and insecticides also contribute to the decline.
One obvious way to help all pollinators is to stop using chemical pesticides and herbicides. As long as the use of these poisons continues, pollinators will die. But people can take steps to support monarchs. One of these is growing milkweed.
Before digging up the yard, itâ€™s important to understand a few things about this wildflower.
If enough is consumed, milkweed is toxic. But itâ€™s not as bad as it sounds. The United States Department of Agriculture has not included it on the list of noxious plants. Gardeners should take simple precautions: wear gloves, wash hands, teach children not to eat the plant, and keep a casual eye on pets. The good news is that while milkweed is delicious to monarchs, it apparently tastes quite dreadful to everyone else. Most animals wonâ€™t even take a nibble. (Interestingly, the toxicity is part of what protects the monarch caterpillar. Evidently, they taste yucky too.)
All milkweeds are not equal. Native milkweeds are perennial, dying off during winter months. The tropical variety (Asclepias curassavica) appeals to many gardeners and suppliers because it grows year-round in mild climates. â€śThe tropical variety is beautiful. It has large leaves and substantial stalks that allow butterflies to land to eat. The butterflies love them,â€ť says Bill Buerge, owner of the Mountain Mermaid Butterfly Habitat, but he advises to plant native varieties.
Ongoing research suggests that winter-breeding butterflies, those who are sustained by the tropical milkweed, are more likely to be infected with Ophryocystis elektroscirrha (OE), a parasite that causes mortality and lowers the monarchâ€™s ability to reproduce. A well-meaning but ill-informed gardener could end up endangering rather than nurturing the beautiful butterfly.
Buerge also advises caution when buying any milkweed. Make sure the plants have not been treated with pesticides. Many garden stores use pesticides to keep their plants pristine until they can be sold.
Before entering the chrysalis phase, a monarch caterpillar can munch through a one-gallon milkweed plant. So, you want to be sure you have enough food to support the life cycle. Always plant a patch of at least six plants. Also consider growing more than one patch to ensure the survival of the plants in unpredictable weather conditions.
Doug Tallamy, Professor of Entomology and author of Bringing Nature Home and Natureâ€™s Best Hope, explains that we need to act quickly to save our insects, the backbone of our ecosystem.
â€śAbout 95 percent of the U.S. has been used by us in one way or another,â€ť said Tallamy at an event hosted by New Canaan Pollinator Pathway. â€śWeâ€™ve logged, tilled, drained, grazed, paved, developed, straightened, dammed, polluted, and introduced non-native species into our natural environment, but we can save ourselves, by changing the way we landscape,â€ť says Tallamy.
By planting native species, we support the insects and other animals who depend on them. This will go a long way to reversing some of the damage weâ€™ve already done.
â€śTopanga has been evolving for millions of years,â€ť says Buerge. â€śMan has brought in ornamentals and the butterflies donâ€™t know what to do with them.â€ť By planting patches of native milkweed in the yard to support the monarchs, a step is taken backward, back in the direction of a thriving ecosystem and a sky filled with fluttering wings.
Center for Biological Diversity, https://biologicaldiversity.org/w/news/press-releases/eastern-monarch-butterfly-population-plunges-more-half-2020-03-13/
United States Department of Agriculture, https://plants.usda.gov/java/noxComposite
Monarch Joint Venture, https://monarchjointventure.org/
Wheeler, J. (2018). â€śTropical milkweed â€“ a No-Grow, retrieved from https://xerces.org/blog/tropical-milkweed-a-no-grow on 7/4/20.