A grasshopper has been found trapped inside a 128-year-old Vincent van Gogh painting.

A Kansas City museum made the discovery when they put the canvas under the microscope.

The Nelson-Atkins Museum of Art came across the tiny dried, brown carcass in the lower foreground while studying the painting of Olive Trees.

The find, announced this week, reflects the artist's practice of painting in the outdoors, where it was often windy enough to send dust, grass and insects flying.

"I must have picked up a good hundred flies and more off the four canvases that you'll be getting, not to mention dust and sand," Van Gogh mused in an 1885 letter to his brother Theo.

"When one carries them across the heath and through hedgerows for a few hours, the odd branch or two scrapes across them."

Conservator Mary Schafer said: "The fact that we have this little surprise of a grasshopper is a fun way to have a new look at a Van Gogh."

She added: "I was mainly trying to understand the different layers of the painting and how it was constructed, and that's how I came upon part of the body of this little grasshopper."

But Van Gogh was no bug killer.

Paleo-entomologist Michael Engel of the University of Kansas told the museum's team that the grasshopper's thorax and abdomen were missing, and no sign of movement was evident in the paint around the insect, indicating it was already dead when it landed on Van Gogh's canvas.

Olive Trees is part of a series of 18 paintings Van Gogh completed on the subject in 1889 in Saint-Remy-de-Provence, France, where he had checked himself into an asylum. He died the following year.

Sand also was found in Seascape near Les Saintes-Maries-de-la-Mer (1888), a work he is believed to have painted from the beach on the Mediterranean.