Long-tailed mayflies (Palingenia longicauda) at Tisza river near Tiszainoka 135km (84 miles) southeast of Budapest, June 23, 2013. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

Pope Francis greets the crowd from his popemobile in downtown Rio de Janeiro. Pope Francis touched down in Rio de Janeiro on Monday, starting his first foreign trip as pontiff and a weeklong series of events expected to attract more than a million people to a gathering of young faithful in Brazil, home to the world's largest Roman Catholic population. (Photo by Ueslei Marcelino/Reuters)

Rachel Hollon of Los Angeles was body painted as Harley Quinn at Comic-Con International in San Diego, USA on Jule 20, 2017. (Photo by K.C. Alfred/San Diego Union-Tribune via ZUMA Press/Rex Features/Shutterstock)

A cyclist drives past a flowering rapeseed field not far from the small Bavarian village of Schoengeising, near Munich, during a nice, warm sunny weather day on May 17, 2017. (Photo by Christof Stache/AFP Photo)

A tomtit bird flies past a squirrel running on a fence after a snowfall in a park in Almaty, Kazakhstan, January 12, 2016. (Photo by Shamil Zhumatov/Reuters)

A sledding dog is covered in ice after spending the night in the open air with his musher at the polar base of Val-Cenis, as they ready for the next stage of the 12th edition of “La Grande Odyssee” sledding race across the Alps on January 17, 2016 in Val Cenis Lanslevillard. (Photo by Jean-Philippe Ksiazek/AFP Photo)

People look at huge waves crashing on the San Esteban de Pravia seafront, northern Spanish region of Asturias February 8, 2016. (Photo by Eloy Alonso/Reuters)

A vendor decorates a sacrificial camel ahead of the Eid al-Adha festival, in Karachi, Pakistan, 23 August 2016. Eid al-Adha is the holiest of the two Muslims holidays celebrated each year, with this year will be celebrated on 02nd September. Eid al-Adha marks the yearly Muslim pilgrimage (Hajj) to visit Mecca, the holiest place in Islam. Muslims slaughter a sacrificial animal and split the meat into three parts, one for the family, one for friends and relatives, and one for the poor and needy. (Photo by Rehan Khan/EPA)