Tropical milkweed, also known as Asclepias curassavica, is a popular plant among gardeners due to its vibrant flowers and ability to attract butterflies, particularly monarch butterflies. However, planting tropical milkweed can have negative consequences for both the monarch population and the overall ecosystem. Let me explain why it is considered bad to plant this particular species of milkweed.
1. Disrupting Monarch Migration: Monarch butterflies are known for their incredible long-distance migration, spanning thousands of miles from Canada and the United States to Mexico. This migration is essential for their survival, as it allows them to find suitable breeding and overwintering grounds. However, planting tropical milkweed can disrupt this natural migration pattern.
2. Delaying Migration: Tropical milkweed has a longer flowering season compared to native milkweed species. While this may seem like a positive trait, it can actually be detrimental to monarchs. Monarchs rely on environmental cues, such as decreasing daylight and cooler temperatures, to trigger their migration. When tropical milkweed continues to bloom late into the fall, it can confuse monarchs and delay their migration, potentially exposing them to harsh weather conditions or limiting their ability to find suitable overwintering sites.
3. Disease Transmission: One of the most significant concerns associated with planting tropical milkweed is the spread of a debilitating monarch butterfly disease called Ophryocystis elektroscirrha (OE). OE is a protozoan parasite that infects monarchs and can weaken their immune system, impairing their ability to fly and reproduce. Tropical milkweed, being a non-native species, often stays green and retains its leaves during the winter, providing a continuous habitat for the OE spores. Monarchs that come into contact with infected plants can easily contract the disease, perpetuating its spread within the population.
4. Increased Competition: Another issue with tropical milkweed is its ability to outcompete native milkweed species. Native milkweed plants have evolved with monarch butterflies and provide the ideal food source for their caterpillars. When tropical milkweed is introduced, it can attract monarchs away from native milkweed, reducing the availability of suitable food and breeding sites for monarch caterpillars. This can ultimately impact the monarch population’s ability to reproduce and thrive.
5. Ecological Imbalance: Planting large quantities of tropical milkweed can disrupt the balance of native plant communities. Native plants have evolved over time to support a diverse range of native insects, birds, and other wildlife. When non-native species like tropical milkweed dominate an area, it can alter the ecological dynamics, potentially leading to a decline in native species diversity and negatively impacting the overall ecosystem health.
It is important to note that not all milkweed species have the same negative impacts as tropical milkweed. Native milkweed species, such as Asclepias incarnata or Asclepias tuberosa, are better choices for supporting monarch butterflies and maintaining a healthy ecosystem. These native species naturally die back in the winter, reducing the risk of disease transmission and allowing monarchs to follow their natural migration patterns.
As a gardener and lover of nature, I have personally witnessed the negative effects of planting tropical milkweed. Monarchs that were supposed to continue their migration during the fall ended up staying in my garden, attracted by the abundant flowers of tropical milkweed. This delay in their migration made me realize the importance of planting native milkweed species and providing a suitable habitat for monarchs to complete their life cycle and continue their incredible journey.
Planting tropical milkweed can have detrimental effects on monarch butterflies and the overall ecosystem. By understanding the potential negative consequences and opting for native milkweed species, we can help support monarch populations and maintain a healthy and balanced environment for all species to thrive.
