Like most Impressionists Vincent Van Gogh liked to paint outdoors, setting up his easel in front of the very landscape he was painting in order to properly capture it's splendor.
And since Van Gogh applied a liberal amount of paint to the canvas to create the signature textural look of his paintings bugs would often get stuck in the globs of paint while they dried.
Van Gogh once wrote in an 1885 letter to his brother "I must have picked up a good hundred flies and more off the four canvases that you’ll be getting", so he was obviously used to having insects add their impression to his paintings.
But as conservators at the Nelson-Atkins Museum of Art in Kansas City, Missouri discovered Van Gogh must have missed a few bugs along the way, because they found a grasshopper embedded in his 1889 painting Olive Trees.
Conservator Mary Schaefer discovered the insect, which she hoped University of Kansas entomologist and paleontologist Michael Engel could use to identify the exact season when the painting was created.
Sadly the insect didn't yield any clues to when the painting was created, but I bet conservators around the world will start poring over their paintings looking for embedded bugs!
-Via Mental Floss