A silkmoth that has hatched out of its cocoon is seen at the Campoverde cooperative, Castelfranco Veneto, Italy June 4, 2015. Despite having wings, the adult moth cannot fly. Clusters of silkworms munch on piles of locally-grown mulberry leaves in a white marquee in Italy's northern Veneto region. They are nourishing hopes of a revival of Italy's 1,000 year-old silk industry. (Photo by Alessandro Bianchi/Reuters)

A three month old white Bengal female tiger cub looks around her enclosure at the Buenos Aires Zoo, Argentina, Wednesday, April 16, 2014. Cleo, a captive Bengal white tiger at the zoo, gave birth to two females and one male white tiger cubs on January 16, 2014. (Photo by Natacha Pisarenko/AP Photo)

The double compound eyes of a male St. Mark's fly (Bibio marci), submitted by Dr. David Maitland from Feltwell, UK. (Dr. David Maitland)

People with his face covered in oil and soot and carrying bull horns representing a devil join a carnival festival on February 14, 2015 in Luzon, Spain. (Photo by David Ramos/Getty Images)

China's Shang Chunsong prepares to compete in the uneven bars event of the women's individual all-around final artistic gymnastics competition at the Namdong Gymnasium Club during the 17th Asian Games in Incheon, in this September 23, 2014 file photo. (Photo by Kim Hong-Ji/Reuters)

Armed female members of the militant Palestinian group Islamic Jihad carry Kalashnikov assault rifles as they take part in a rally to protest against US President Donald Trump's decision to recognise Jerusalem as the capital of Israel, in Gaza City on December 11, 2017. (Photo by Mohammed Abed/AFP Photo)

Jack, a Lurcher from Dogs Trust Salisbury, walks past a window display of models in a Dogs Trust shop window in Salisbury, as part of a campaign to discourage the impulse buying of dogs ahead of Valentine's Day, on February 10, 2014. (Photo by Matt Alexander/PA Wire)

Comandos de Salvamento rescuers Maria Martinez (L) and Ana Chichilla attend to a wounded homeless man in San Salvador, El Salvador July 16, 2016. The man was attacked with a machete by suspected gang members. In 2015, El Salvador registered a record 103 homicides per 100,000 habitants, making it one of the most dangerous countries in the world outside a war zone. But for many young people who have few chances to distance themselves from rivalries between so-called maras in their schools and neighbourhoods, a civil-society organisation called the Comandos de Salvamento, or Rescue Corps, has been a refuge. (Photo by Jose Cabezas/Reuters)