Monarch Butterfly

"The Endangered migratory monarch butterfly is a subspecies of the monarch butterfly (Danaus plexippus). The native population, known for its migrations from Mexico and California in the winter to summer breeding grounds throughout the United States and Canada, has shrunk by between 22% and 72% over the past decade. Legal and illegal logging and deforestation to make space for agriculture and urban development has already destroyed substantial areas of the butterflies’ winter shelter in Mexico and California, while pesticides and herbicides used in intensive agriculture across the range kill butterflies and milkweed, the host plant that the larvae of the monarch butterfly feed on. Climate change has significantly impacted the migratory monarch butterfly and is a fast-growing threat; drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies. The western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021. The larger eastern population also shrunk by 84% from 1996 to 2014. Concern remains as to whether enough butterflies survive to maintain the populations and prevent extinction."

The 2016 monarch count showed that over the past 22 years, these butterflies declined by 68 percent, with the population at 150 million butterflies — not the most devastating of declines, and wonderful news considering the truly alarming count in 2015 of just 42 million, the second-lowest ever since surveys began in 1993.

Fewer monarch butterflies are crossing North America to winter in Mexico, and the biggest culprit seems to be the disappearance of milkweed in the United States. The trend is particularly troubling because monarchs have long been considered both an indicator of our ecological health and a representative of pollinator populations...

President Obama issues a presidential memorandum, followed in 2015 by a plan to create a taskforce “to promote the health of honey bees and other pollinators,” including building a “pollinator highway” to help the butterflies travel down the length of the country to Mexico. The task force set a goal to increase the Eastern population of the monarch butterfly to 225 million.

The Lowest Numbers Of Monarch Butterflies Ever Recorded At Overwintering Sites In Mexico (34 Million Individuals)

What we're seeing here in the United States is a very precipitous decline of monarchs that's coincident with the adoption of Roundup-ready corn and soybeans. The first ones were introduced in 1997, soybeans first, then corn. By 2003, 2004, the adoption rate was approaching 50 percent, and then we really began to see a decline in monarchs... the use of Roundup has... effectively eliminated milkweed from almost all of the habitat that monarchs used to use.

Dr. Fred and Norah Urquhart developed small labels to tag the Monarch butterflies and study their migration.... they... founded the Insect Migration Association (known today as Monarch Watch), enlisting thousands of volunteers across North America to tag hundreds of thousands of butterflies in order to track their migration route. In 1975, this association ultimately helped Dr. Urquhart determine where millions of butterflies migrated – the remote Transvolcanic Belt of central Mexico.

“From the north they came ... to the south they swept away ... as far as I could see them-to Texas, to Louisiana, to Mexico”, and “all along the Canada line east and west the mighty winged host of monarchs advances, when instinct stirs, straight down across the states to Mexico”

“The multitude of this butterfly that assembled here the first week in September is almost past belief. Millions is but feebly expressive—miles of them is no exaggeration.… After three o'clock these butterflies, coming from all directions, began to settle on the bushes, and by evening every available twig was occupied. To see such multitudes at rest, all suspended from the lower sides of the limbs, side by side, as is their well-known custom, was something well worth seeing”

The common name monarch was first published by the naturalist and lepidopterist Samuel H. Scudder in 1874 because “It is one of the largest of our butterflies, and rules a vast domain.”

“...on the lee sides of trees, and particularly on the lower branches, as almost to hide the foliage, and give to the trees their own peculiar color.”