The Metropolitan Museum of Art has an interesting five-and-a-half-minute video in which they talk about this painting. In it they call The Harvesters "the first modern landscape in western art." I would like to have shown the video here, but it is only available at the site, so click here to watch it. Look just below on this post to see the other paintings in this series that have survived.
April-May is the missing picture
The Hay Harvest - June-July
August-September is the picture at the top of this post:
The Harvesters, also known as The Wheat Harvest
The best biography of Pieter Bruegel the Elder that I have been able to find online.