Ants carry a leaf with a slogan reading “Merkel, Help!”, a reference of German Chancellor Angela Merkel, at the zoo in Cologne, Germany August 18, 2015. Some of the zoo's 500,000 leaf-cutting ants carry laser-cut leaves with slogans during a campaign to protect the Amazon rain forest, organised by the German branch of World Wild Fund for Nature (WWF) and Cologne Zoo. Picture taken through the glass of the display case. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “Help!” at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “Merkel, Help!”, a reference of German Chancellor Angela Merkel, at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “Forest = Future” at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “!Pro! Amazon” at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “!Pro! Amazon” at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Ants carry a leaf with a slogan reading “Merkel, Help!”, a reference of German Chancellor Angela Merkel, at the zoo in Cologne, Germany August 18, 2015. (Photo by Ina Fassbender/Reuters)

Leaf-cutting ants carrying a leaf that has the world “Hilfe!” (Help!) carved into it run through a pipe in the zoo of Cologne, Germany, 18 August 2015. Nature conservation group WWF used ants to gather support for the preservation of rainforests prior to German-Brazilian government talks. (Photo by Oliver Berg/EPA)