The Monarch butterfly is known all over the world as one of the most iconic insects. Its black, orange and white wings can be recognized instantly. Monarch butterflies are also famous for their migration from Canada and regions east of the Rockies, all the way to Mexico. It takes four generations to complete this long journey, which means a place for Monarchs to lay their eggs is crucial. Milkweed is the only plant the Monarch caterpillars can eat. When Monarchs lay their eggs on plants similar to milkweed, such as the black swallow-wort, the caterpillars will hatch but will be poisoned and die as soon as they start to eat the plant. In recent years, there has been a huge decrease in milkweed plants due to an increased use of agricultural herbicides and weed killers in general. Without a place to lay their eggs, the monarchs cannot continue their annual migration and are at risk of extinction.