A monarch butterfly rests on the ground at the Sierra Chincua butterfly sanctuary on a mountain in Angangeo, Michoacan November 24, 2016. Angangueo is a town and municipality located in far eastern Michoacán state in central Mexico noted for its history of mining and its location in the Monarch Butterfly Biosphere Reserve. The Monarch Butterfly Biosphere Reserve is a World Heritage Site containing most of the over-wintering sites of the eastern population of the monarch butterfly. (Photo by Carlos Jasso/Reuters)

Eugloss dilemma, male, Florida, Biscayne National Monument. (Photo and caption by Sam Droege/USGS Bee Inventory and Monitoring Lab)

British prime minister Winston Churchill (1874–1965) stops to pet a cat at Liverpool Street Station, 24th May 1952. (Photo by Keystone/Hulton Archive/Getty Images)

A marcher dressed as Marilyn Monroe during the annual Gay Pride march in London, July 1994. (Photo by Steve Eason/Hulton Archive/Getty Images)

A female rebel in Kabul, Afghanistan, circa 1979. Photo taken at a parade in Kabul in honor of the pro-Communist Saur Revolution. She was from the women’s battalion of the people’s militia (one of the anti-imperial groups that participated in the coup d’etat). (Photo by Viktor Khabarov)

Three members of English pop group The Tremeloes; Chip Hawkes, Alan Blakley and Dave Munden, kissing their brides; Carol Dilworth, Lyn Stevens and Andree Wittenberg, in Trafalgar Square, London. (Photo by Wesley/Getty Images). 1967

Two men using an electric power saw to fell a tree circa 1940's. (Photo by Keystone View/FPG/Getty Images)

Soviet Army soldiers sit on their tanks in front of the Czechoslovak Radio station building in central Prague during the first day of Soviet-led invasion to then Czechoslovakia on August 21, 1968. (Photo by Libor Hajsky/Reuters)