Excerpt:

“It is not unusual to find insects or plant material in a painting that was completed outdoors,” Ms. Schafer said in a statement. “But in this case, we were curious if the grasshopper could be used to identify the particular season in which this work was painted.”

The museum reached out to Dr. Michael S. Engel, a professor of ecology and evolutionary biology at the University of Kansas, who determined that the grasshopper was dead before it landed on van Gogh’s canvas because there was no movement in the surrounding paint. Nothing further about the time of year that the painting was worked on could be determined.

Van Gogh died in 1890, the year after he completed “Olive Trees.” In 1885, van Gogh had described his frustration with working with landscapes outside 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 four canvases that you’ll be getting, not to mention dust and sand.”