Milkweed, Asclepias syriaca
Look carefully at this plant — do you see any tiny monarch eggs on the leaves, or perhaps a striped monarch caterpillar munching away? In autumn, watch as the pods burst open and release their silky seeds into the wind!
Milkweed is a plant most favored by monarch butterfly larvae and other insects looking for a sweet snack in the summer. This plant can reach almost 9ft tall and is native to the eastern half of the US. It’s been introduced to Europe and also made its way west to Oregon, where it may be recognized as an invasive species, depending on the environment. Recently, pesticide use has caused milkweed populations to fall, which coincides with a sharp drop in monarch butterfly populations. Deforestation can actually aid distribution of milkweed but also spells trouble for monarchs which rely on trees for roosting away from predators.
While the problem is complicated, research suggests that planting more milkweed in migration paths for monarch butterflies will help the species recover from population declines. This especially includes areas between Central Mexico, where monarchs winter, and the northern US/Great Lakes region, where they head for summer.
While milkweed is an important food source for monarch larvae, parts of the plant may be poisonous to other animals and humans. Instead of eating it, humans can use its milky oil as sunscreen or plant it to help monarchs and other important pollinators. If a species like the monarch butterfly is largely dependent on a single food source, what would happen if that plant disappears? How might this affect other parts of the broader food web?