A butterfly is seen in the Butterfly Garden at Zoo Budapest in Budapest, Hungary, on June 6, 2019. Zoo Budapest opened it's Butterfly Garden for the current season with about 21 species of tropic butterflies. (Xinhua/Attila Volgyi)

A butterfly is seen in the Butterfly Garden at Zoo Budapest in Budapest, Hungary, on June 6, 2019. Zoo Budapest opened it's Butterfly Garden for the current season with about 21 species of tropic butterflies. (Xinhua/Attila Volgyi)

A butterfly is seen in the Butterfly Garden at Zoo Budapest in Budapest, Hungary, on June 6, 2019. Zoo Budapest opened it's Butterfly Garden for the current season with about 21 species of tropic butterflies. (Xinhua/Attila Volgyi)

A butterfly is seen in the Butterfly Garden at Zoo Budapest in Budapest, Hungary, on June 6, 2019. Zoo Budapest opened it's Butterfly Garden for the current season with about 21 species of tropic butterflies. (Xinhua/Attila Volgyi)

A butterfly is seen in the Butterfly Garden at Zoo Budapest in Budapest, Hungary, on June 6, 2019. Zoo Budapest opened it's Butterfly Garden for the current season with about 21 species of tropic butterflies. (Xinhua/Attila Volgyi)