Grasshopper found embedded in Vincent Van Gogh's Olive Trees painting

This photo provided by The Nelson-Atkins Museum of Art in Kansas City, shows Vincent van Gogh's painting 'Olive Trees' which has recently revealed a secret. Photo / AP

Museum curators have made a surprise discovery in Vincent Van Gogh's Olive Trees: a grasshopper embedded in the paint.

The experts from the Nelson-Atkins Museum of Art in Kansas City discovered the insect - missing its abdomen and thorax - 128 years after it was painted.

Van Gogh was a famous proponent of plein air painting - the practice of painting outdoors - and it is thought the grasshopper unintentionally became part of the canvas while the artist was at work outside.

"Van Gogh worked outside in the elements," Julián Zugazagoitia, the Nelson-Atkins Museum of Art director, told the Kansas City Star. "And we know that he ... dealt with wind and dust, grass and trees, flies and grasshoppers."

A small grasshopper found embedded in the thick paint in the lower foreground of Vincent van Gogh's 'Olive Trees' painting. Photo / AP

The grasshopper was spotted by the curators during a cataloging project. It is camouflaged in the brown and green colours in the foreground of the painting.

Mary Schafer, the gallery's paintings conservator, made the discovery while examining the canvas with a magnifying glass. She initially thought it was a leaf.

"It's not unusual to find this kind of material in paint," Ms Schafer told Architectural Digest. "But the grasshopper's discovery connects viewers with van Gogh's painting style, and the moment in which he made the work."

In 1885, Van Gogh wrote about the process - and challenges - of painting outdoors in a letter to his brother, Theo.

"But just go and sit outdoors, painting on the spot itself! Then all sorts of things like the following happen - I must have picked up a good hundred flies and more off the 4 canvases that you'll be getting, not to mention dust and sand ... when one carries a team of them across the heath and through hedgerows for a few hours, the odd branch or two scrapes across them," Van Gogh wrote.

Michael Engel, a paleo-entomologist from the University of Kansas, suggested that, because there was no sign of movement in the paint, the grasshopper could have been dead when it fell onto the canvas.

The Dutch master committed suicide a year after completing Olive Trees, in 1890.