Countless pairs of eyes have gazed at Vincent van Gogh’s “Olive Trees” and not seen it.

Yet, it’s been right there in the foreground, embedded in the paint, for 128 years.

A grasshopper. Well, part of one. It’s missing its thorax and abdomen, but it’s definitely a real grasshopper.

“Van Gogh worked outside in the elements,” said Julian Zugazagoitia, director of the Nelson-Atkins Museum of Art, where “Olive Trees” resides, “and we know that he … dealt with wind and dust, grass and trees, and flies and grasshoppers.”

The troubled artist, who took his own life a year after “Olive Trees” was painted in St.-Remy, France, had groused about it in an 1885 letter to his brother, Theo.

“But just go and sit outdoors, painting on the spot itself!” Vincent wrote. “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.”

A team of curators, conservators and outside scientists had been doing more research on the 104 French paintings in the Nelson’s collection. Conservator Mary Schafer was looking at the oil painting under magnification when she discovered the grasshopper.

She was curious if the insect could shed light on the season in which the painting was created. It could not.

But paleo-entomologist Michael Engel of the University of Kansas reported there was no sign of movement in the surrounding paint, indicating the grasshopper was dead when it fell onto the canvas.

The Nelson left the painting intact without removing the insect. Casual visitors looking at “Olive Trees” in the museum’s Bloch Galleries will not notice the grasshopper.

But now we know it’s there.