The butterfly population has declined steadily up to 90 percent over the last 20 years due to habitat loss associated with the farm.
It is estimated that one billion monarchs migrate to Mexico in 1996, but last year, only 35 million are believed to have made the same trip.
Agriculture is destroying milkweed plants that monarchs are based on asking and nourish their eggs and larvae. Crops genetically modified to resist herbicides, but native plants like milkweed, lack immunity and die.
Exploring the mountain forests in central Mexico and off the coast of California, where Kings migrate for the winter, are also threatening its population, according to Karen Oberhauser biologist at the University of Minnesota.
Yesterday, the US Fish and Wildlife said a petition asking the government to issue monarchs of protection "presents substantial information indicating that the [the butterfly as an endangered species] can be justified".
"Almost everyone I talked about monarchs expressed their love and admiration for them that often formed in childhood," said Oberhauser.
What is your favorite butterfly?