Darwin and his fellow naturalist, Alfred Russel Wallace, made predictions about the existence of the Sphinx Wallace Moth, which symbiotically interacts with orchids that have very long nectar tubes. In 1862, Charles Darwin received a Madagascan orchid through the mail. Its flower has a very long nectar tube, called a spur, measuring one foot (30 centimeters) in length.

The two naturalists were proven right when the long-tongued moth was finally discovered in Madagascar. In 1903, the moth was identified as a subspecies of the Morgan's sphinx moth (Xanthopan morganii) and given the scientific name X. m. praedikta. The predicted pollination by Darwin and Wallace could only be observed and photographed in the 1990s.