Migrating monarch butterflies (Credit: Gene Nieminen/U.S. Fish and Wildlife Service, via Flickr)
The number of monarch butterflies migrating south to Mexico has declined in recent years, according to National Geographic Magazine. In 2004, about 550 million butterflies migrated. Last year, only 33 million made it.
Bad weather and excessive deforestation have contributed to the decrease in the monarch butterfly population. However, research indicates disappearing milkweed is the biggest threat. Over 18 years, the plant’s presence has dropped by 21 percent due to U.S. farmers’ use of herbicides.
Milkweed is crucial to monarch survival; the butterflies will only lay their eggs on it. The growing caterpillars also eat the plant. To aid recovery, preservationists, researchers and butterfly hobbyists are urging people to plant milkweed in their yards.
Image: Migrating monarch butterflies (Credit: Gene Nieminen/U.S. Fish and Wildlife Service, via Flickr)