The western harvester ant nests are covered with similar-sized pieces of gravel. How do these little bugs move what must be the equivalent of a 50-lb rock to us? They make it look so easy! An interesting side note: paleontologists often find tiny fossils such as mouse teeth on these nests, which makes one wonder how many times they get stung ransacking a harvester ant nest! The gravel not only helps keep the sand nest from blowing away in the often-fierce desert winds, but also help regulate temperature. I've seen these guys working just as hard at night - must be the graveyard shift. Filmed in Dinosaur National Monument, Colorado.