The population of monarch butterflies throughout the United States has been decreasing rapidly over the years. According to MonarchWatch.org, from 2013 to 2014 the population of monarch butterflies in the East was less than 100 monarchs per 100 acres. In the West, the population of monarch butterflies was lower than 25,000. The primary reason behind the decline of the monarch butterfly is the decline of the milkweed — the only known larval food source — as a result of herbicide usage by farmers.
Monarchs are pollinators, who are active throughout the day and visit a variety of wildflowers. According to the USDA, monarchs are less efficient than bees when it comes to moving the pollen between plants because they cannot pick up as much pollen due to their long legs. Monarchs search for nectar, their form of fuel, and prefer flowers that are flat because they provide a landing pad. With this in mind, farmers and entomologists alike have studied the probable causes behind the low population of this vital insect.
Reid Smeda, a weed science professor at the University of Missouri, said the milkweed is extremely important for the monarch reproductive development.
“The monarch lays its eggs on the milkweed plant,” Smeda said. “The plant itself serves as a host for the developing caterpillar.”
Milkweed received recognition in the 1950s to the 1960s as an official plant. According to monarchjointventure.org, becoming recognized as an official plant means milkweed has an important role in the monarch’s life when it comes to life development and feeding. Milkweed is known as being a perennial plant and grows in a non-disturbed area, meaning in ditches or roadsides. The main cause of milkweed decline is herbicide usage and farmers expanding their fields in order to grow more crops.
The monarchs view the milkweed along their migration path similar to a gas tank. In order for them to complete their journey and to complete their life cycle, the monarchs need access to milkweed.
Another reason behind the low population of monarch butterflies is habitat destruction. Bruce Barrett, an entomology professor at the University of Missouri, said habitat destruction along the monarch’s migration paths has been an alarming cause to the decreasing population.
“Habitat destruction in the eastern overwintering areas in Central Mexico and in the western overwintering areas in California is one of the reasons why monarch butterfly population continues to go down,” Barrett said.
There are actions being taken to prevent the population of monarch butterflies from declining even further. National, regional and state incentives exist to create a habitat for monarchs. Organizations such as Missouri for Monarchs plants milkweed weigh stations, so monarchs have a place to feed during their migration. National companies such as Monsanto have created the Monarch Butterfly Commitment, a movement that is dedicated to working with researchers, nonprofit organizations and universities to improve monarch butterfly habitats across North America. This commitment also addresses the important element of biodiversity and why it needs to be protected.
Mizzou has 13 research stations located throughout the state that will plant “monarch way stations” to give the travelers a place to rest and refuel, according to an article on the CAFNR website. Altogether, these centers will plant 22 acres of monarch habitat.
The situation may seem grim, but many are starting to realize the important role of the milkweed plant. Farmers are leaving patches of milkweed, so the monarch can feed during their 3,000-mile migration trip that can take up to three generations of monarchs to complete. Actions like this will not fully fix the problem but will, nevertheless, help make a difference.